bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Objective Digital Computerized Vision Screening System
Authors: Granet David B , Hoover Adam , Smith Amanda R , Brown Stuart I , Bartsch Dirk-Uwe , Brody Barbara
Published: April 2021

ABSTRACT

Purpose: Fewer than 40% of children in the crucial younger-than-4 age group are evaluated for visual problems by pediatricians. This is due to impracticality from either a clinical or practice efficiency standpoint. Current photoscreening methods require trained readers and suffer from significant subjectivity and interobserver variability. We report a cross-sectional, double-masked study using new digital imaging with objective, automated, computerized image analysis.

Methods: Two-hundred six children aged 9 months to 16 years were prospectively studied in a University-based pediatrie ophthalmology practice. Images were taken by volunteers with a modified digital camera which, when downloaded, were analyzed within 35 seconds by new image analysis software. The analysis was compared to a masked review of a complete pediatrie ophthalmic exam.

Results: Overall agreement between physician and the objective computerized analysis was 86.9%. Positive predictive value was 91%, sensitivity was 89%, and specificity was 83%.

Conclusions: This automated digital imaging screening system eliminates human bias and provides accurate and immediate results. The system requires no special expertise.

Journal of Pediatrie Ophthalmology and Strabismus 1999;36:251-256.
Bilateral Posterior Fixation Sutures on the Medial Rectus Muscles for Correction of Nonaccommodative Esotropia With Infantile Onset Criteria
Authors: Rizk Akmal
Published: April 2021

ABSTRACT

Background: Bilateral posterior fixation sutures on the medial rectus muscles can be used in the management of nonaccommodative esotropia with criteria indicative of infantile onset. The postoperative results of posterior scierai fixation of bilateral medial rectus muscles on ocular motility and the angle of esotropia in different directions of gaze, as well as on the near point of convergence, have been studied.

Methods: Twenty-six patients suffering nonaccommodative esotropia of the infantile onset type, showing variable angles, adduction overshooting, and esodeviation, which had started within the first year of life, were examined. The angle of esotropia was measured at near, distance, and in the different directions of gaze. All patients underwent postequatorial scierai fixation of both medial rectus muscles at 12 mm to 14 mm from the insertion, depending on the preoperative angle of esotropia.

Results: With the alternate prism cover test, 20 patients (76.9%) showed an angle <10 prism diopters (?) in the primary position, as well as in the different directions of gaze. Fifteen of the 20 patients (57.7%) even showed simultaneous perception at near and at distance with Bagolint's striated glasses. Six patients were under-corrected.

Conclusions: Bilateral posterior fixation of the medial rectus muscles is a good procedure to correct the angle of esotropia in patients who meet the following criteria: essential infantile esotropia, showing overacting medial rectus muscles, variable angles, and nonaccommodative convergence excess.

Journal of Pediatrie Ophthalmology and Strabismus 1999;36:320-325.
Visual Capacity and Prader-Willi Syndrome
Authors: Fox Robert , Sinatra Robbin B , Mooney Megan A , Feurer Irene D , Butler Merlin G
Published: April 2021

ABSTRACT

Purpose: Prader-Willi syndrome (PWS) refers to a genetic disorder induced by an anomaly on chromosome 1 5 occurring with a frequency of one in 10,000 to 20,000. It is characterized by a unique set of features including infantile hypotonia, obesity in childhood, small hands and feet, hypogonadisrn, and mental retardation. Reported here are the results of ophthalmic examinations of persons with PWS, together with results from controls comparable in age, percentage of body fat, and intelligence. These data bear on the hypothesis that the ocular anomalies in PWS are unique to this syndrome.

Method: A comprehensive investigation of PWS brought children and adults to Vanderbilt University for extended testing, which included an ophthalmic examination. Genetic analysis determined unequivocally the PWS diagnosis and identified subgroups - deletion and maternal disomy. A group of persons without PWS but generally comparable in age, body composition, and intelligence served as controls.

Results: Significant differences between the deletion and disomy subgroups were not found for the clinical ophthalmic measures. The incidence of anomalies in the combined PWS was similar to those reported in previous studies. A similar pattern was present in the control group except for myopia and stereopsis. An effect of genetic subgroup, however, was observed for random element stereopsis with the maternal disomy group having a greater degree of impairment.

Conclusion: The overall similarity between the PWS and control groups on all measures except myopia and stereopsis suggest that many of the anomalies in PWS found in prior studies are due to factors inherent in a general dysfunctional population, rather than reflective of an ocular signature unique to PWS.

Journal of Pediatrie Ophthalmology and Strabismus 1999;36:331-336.
Maldevelopment of Neural Crest Cells in Patients With Typical Uveal Coloboma
Authors: Ozeki Hironori , Shirai Shoichiro , Nozaki Miho , Ikeda Kozo , Ogura Yuichiro
Published: April 2021

ABSTRACT

Purpose: To clarify the pathogenesis of ocular and systemic anomalies associated with typical uveal coloboma.

Methods: The records of 72 patients with typical uveal coloboma (35 males and 37 females) treated at Nagoya City University Hospital during a 16-year period were reviewed.

Results: Typical uveal coloboma was bilateral in 33 patients and unilateral in 35 patients; 4 patients were unclassified because of severe contralateral micraphthalmos. Uveal coloboma was an isolated defect in 23 (37%) patients. Other ocular anomalies were present in 19 (31%) patients, systemic anomalies were found in 7 (11%) patients, and both other ocular and systemic anomalies were noted in 13 patients (21%). The associated ocular anomalies included microphthalmos in 28 eyes of 23 patients, persistent pupillary membrane in 28 eyes of 18 patients, and posterior embryotoxon in 20 eyes of 15 patients. The accompanying systemic anomalies included ear anomalies, retarded growth, and retarded development in 18 patients; heart anomalies in 1 3 patients; genital hypoplasia in 1 2 patients; and congenital facial palsy in 10 patients. The collection of malformations known as the CHARGE association was diagnosed in 14 (19%) patients.

Conclusion: Abnormal development of neural crest cells appeared to be responsible for the majority of associated ocular and systemic anomalies in patients in the present series, suggesting that typical uveal coloboma may be related to maldevelopment of the neural crest cells. The present findings indicated that ophthalmologists should be aware of the possible association of typical uveal coloboma with systemic anomalies.

Journal of Pediatrie Ophthalmology and Strabismus 1999;36:337-341.
The Traditional Treatment of the Psychiatric Patient in Nigeria
Authors: Daramola S O
Published: April 2021

ABSTRACT

Fifty Yoruba male patients were interviewed in an outpatient psychiatric clinic in Abeokuta, Nigeria. The interview revealed that most Yoruba people seek traditional healers for their physical and emotional illnesses. The type of treatment obtained from the healers has a significant meaning for each patient who seeks that kind of treatment. The native healers and the (Aladura) Church sect are commonly patronized, followed by the (Alfa) Moslem healers. The type of treatment received by the patients were: native drugs, charms to wear, venesection, exorcism, prayers with candlelight, animal sacrifice, medicinal water for washing, and restraint. A few patients attended the general hospital and health center where they received drugs and injections. It was only a negligible percentage of the patients who sought direct psychiatric care, when they were emotionally ill.
Remarriage: Parental Perceptions of Steprelations with Children and Adolescents
Authors: Palermo Eleanor
Published: April 2021

ABSTRACT

This study was designed to determine if relationships between stepparents and adolescents differed from those between stepparents and younger children. Utilizing a questionnaire developed by Duberman,1 responses from remarried couples (N=50) were used to determine a steprelationship score for each child. The scores for children under age 13 and 13 and over both at the time of the parental marriage termination and the remarriage were compared. Chi-square techniques were used in the data analysis. No significant differences were found between the two groups. The results of this study suggest that factors, other than the child's age, may influence the steprelationship. Possibilities suggested include unresolved conflicts in the child and/or parents, the child's relationship with one or both natural parents, or the natural parents' relationship. This population merits further research consideration as society attempts to assimilate the growing numbers of these families.
RESEARCHERS FIND HIGH SUICIDE RATE
Authors: Anonymous
Published: April 2021

EPILEPSY
CHILDREN & YOUTH SERVICES DIRECTORY
Authors: Anonymous
Published: April 2021

REFERENCE GUIDE
The New-Look School Nurse
Authors: Liebow Phoebe Recht
Published: April 2021

Was the 3rd-grader seriously intending to "do away with himself"? the anxious teacher asked.
PRESCRIPTION DRUGS FOR MENTAL HEALTH
Authors: Anonymous
Published: April 2021

BOOKLET
THE STRUGGLE TO GO ON
Authors: Anonymous
Published: April 2021

YOUNG WIDOWS
The Nurse as Leader
Authors: Birckhead Loretta M
Published: April 2021

Group Psychotherapy with Psychotic Patients
COURT VICTORY
Authors: Anonymous
Published: April 2021

UNION NURSES
ALZHEIMER'S DISEASE
Authors: Anonymous
Published: April 2021

CALL FOR. . .
RARE AMONG ELDERLY
Authors: Anonymous
Published: April 2021

ANXIETY DISORDER
Interview with Jerome Frank, Ph.D., MD.
Authors: Anonymous
Published: April 2021

Exploring concepts of influence, persuasion, and healing.
BURN VICTIMS
Authors: Anonymous
Published: April 2021

HYPNOSISHELPS
The EVENING SHIFT
Authors: Hay Marjorie , Drake Nancy L , Lindy Jacob D
Published: April 2021

An Occasion for Acting Out Transference Phenomena
Who Are We?
Authors: Watson Wendy L , Bell Janice M
Published: April 2021

Low Self-Esteem and Marital Identity
DO IT YOURSELF
Authors: Collins-Colon Tina
Published: April 2021

Medication Management for Community Based Clients
The Concept of GUILT
Authors: Robertson W James
Published: April 2021

Functional guilt motivates the individual to repair the harm done and to refrain from future violations.
Counseling Needs of Women With Breast Cancer: What the Women Tell Us
Authors: Trief Paula M , Donohue-Smith Maureen
Published: April 2021

Research has demonstrated that some women treated for breast cancer are at risk for significant and persistent emotional distress and disrupted quality of life. Factors identified that appear to make women psychologically vulnerable include younger age at diagnosis, a history of high life stress or depression prior to diagnosis, and more advanced disease. Research has quickly moved to develop and implement psychological interventions to help these women, although little is known about the patients' perceptions of their need for, and use of, such services. This article presents research that focuses on the perceptions of the women themselves using a survey technique.
Understanding Vicarious Traumatization
Authors: Blair D Thomas , Ramones Valerie A
Published: April 2021

I have this actual, physical reaction when I hear a helicopter, especially a Huey. If il gets close or loud, I feel this adrenaline rush. I shake and start breathing hard. I lose concentration and my mind tries to go off somewhere, oui I don't let it. Because it's embarrassing. If 1 hear helicopters from a distance, I have this compulsion to run outside and see where they are going.

We used to have a great sex life. Then she stopped letting me touch her genital area - she said it was 'like somebody probing her.' She used to like it. I tried being very gentle, but she wouldn't allow it. Then she slarted gelling all panicky and upset when we had intercourse, when I was on top. It gol so the only way we could have sex was if she was on top.

She got strange and wouldn't talk about it - she made me feel like I had done something wrong, or that I had hurt her or forced her in some way. It came from working in that clinic - she took all those stories to heart. She was really screwed up - it destroyed our relationship.

The worst thing that happened was when I was driving to work. Out of the clear blue sky, a utility worker was off to the side of the road working around a manhole. He made a gesture, like he was raising a rifle to shoot me. I flinched and moved away, and nearly ran into the car in the other lane. Looking back I saw he didn't have a weapon, he was just working. That bothered me. especially because I overreacted like that and almost had an accident.

The worst for me is that I can't enjoy watching the kids play sports. 1 just focus in on watching how the coaches and officials touch the children. This obsession ruins these activities for me, I can't seem to focus on the game itself. I know these people are probably really good people, and I admire their volunteering of their time. But they touch the children a lot during the game, and I can't seem to take my eyes away. I've got to keep watch for anything inappropriate.
Cost cutting may be hazardous to your health
Authors: Anonymous
Published: April 2021

Nurses are expected to work harder and faster, providing the same quality of care to more and sicker patients with fewer resources.
Transorbital Lobotomy at Eastern State Hospital (1951-1954)
Authors: Colaizzi Janet
Published: April 2021

'Desperate times' in psychosis treatment
Five-Year Results of Radial Keratotomy
Authors: Sawelson Harold , Marks Ronald G
Published: April 2021

ABSTRACT: We present 5-year findings on 198 consecutive radial keratotomy surgeries. Follow-up was obtained on 134 (68%) of these eyes. Mean spherical equivalent (SE) was -4.3 diopters before surgery, average keratometry was 44,H D, and 75% of eyes had uncorrected distance acuity of 20/400 or worse, Average SE was -0.52 D for eyes seen at 5 years, which compares with -0.78 D for eyes examined at 18 months. Seventeen percent of eyes show at least a 1-D change in refraction from 18 months to 5 years compared with 13% between 18 months and 3 years. Fifty-six percent of eyes are within I D of emmetropia at 5 years, compared with 66% at 18 months. Uncorrected visual acuity was at least 20/40 in 62% of eyes seen at 5 years and in 73% of eyes seen at 18 months. Ten percent of eyes have lost at least two lines of best-corrected visual acuity from before surgery to 5 years later. Factors are identified that relate to loss of uncorrected and best corrected acuity over 5 years. Average keratometry at 5 years is 40.7 D, as compared with 41,2 D at 18 months.

Long-term keratometric results appear less stable than refractive results and a theory for this instability is presented, The results indicate radial keratotomy to be safe and effective for the vast majority of patients in this series for 5 years postoperatively, [Refractive & Corneal Surgery 1989; 5:8-20.]
Inflammatory Cell Responses to Radial Keratotomy
Authors: Anderson Janet A , Murphy Joyce A , Gaster Ronald N
Published: April 2021

ABSTRACT: Radial keratotomy stimulates the influx of polymorphonuclear cells (PMNs) into the tear film and stroma, These cells do not degranulate and are gone in four days. Incisions fill with persistent epithelial plugs, and extracellular matrix (ECM) replacement does not occur, in contrast, a thermal burn stimulates a prolonged influx of PMNs into the tear film and stroma, where they degranulate and remove damaged tissue. ECM replacement in a few weeks suggests that factors released by activated PMNs may stimulate normal wound healing in the cornea. [Refractive & Corneal Surgery 1989; 5:21-26.]
A Comparison of One-Stage Radial Keratotomy With Two-Stage Radial Keratotomy in Myopia
Authors: Thornton Spencer P
Published: April 2021

ABSTRACT: TO determine the efficacy of one-stage compared with two-stage radial keratotomy, a study was designed to compare both eyes of the same patient with moderate myopia; one eye was operated in one stage and the fellow eye in 1wo stages. The surgical technique was identical in all four procedures of the two patients. Although the case for greater effectiveness with one-stage radial keratotomy cannot be proven on the basis of only a few cases, onestage surgery appears to be more effective and more predictable. [Refractive 8c Corneal Surgery 1989; 5:43-45.]
Radial Keratotomy in Myopia of 6 to 12 Diopters Using Full-Length Deepening Incisions
Authors: Bauerberg Jorge , Sterzovsky Marcelo , Brodsky Mauricio
Published: April 2021

ABSTRACT: Radial Keratotomy was performed in 409 eyes with myopia of - 6 to -12 diopters using eight incisions and deepening them from the optic zone to the limbus. The mean preoperative spherical equivalent refraction was - 7.83 D and the mean postoperative was - 1.02 D. Fifty-eight percent of the eyes were corrected io within 1 D of emmetropia and 38% achieved an uncorrected visual acuity of 20/40 or better. [Refractive & Corneal Surgery 1989; 5:150-154.]
Computer-Assisted Corneal Topography in Keratoconus
Authors: Rabinowitz Yaron S , McDonnell Peter J
Published: April 2021

ABSTRACT: Using a computer-assisted videokeratoscope, we determined the topographic findings of 14 eyes of 10 patients with keratoconus. None of these patients had worn contact lenses for at least one year prior to examination and were thus free of contact lens-induced topographical alterations. Two patterns commonly seen included inferior steepening more prominent temporally, and central steepening with a superimposed asymmetric bowtie pattern. When compared with normal eyes three quantitative parameters were significantly different (p <0.001): central corneal power, difference in corneal power between fellow eyes in the same patients, and steepening of the interior cornea compared with the superior cornea. Study of the topography in keratoconus using this technique may prove useful for documenting the pattern of involvement of the anterior corneal surface and providing new insights into the pathogenesis of this condition. [Refractive and Corneal Surgery 1989; 6:400-408].
A Comparison of Surgical Keratometers
Authors: Frantz Jonathan M , Reidy James J , McDonald Marguerite B
Published: April 2021

ABSTRACT: Surgical keratometers were conceived as an aid that would help anterior segment surgeons minimize postoperative astigmatism, a major obstacle along the road to rapid visual rehabilitation. Two classes of surgical keratometers are commercially available at present. The first class of devices produces a keratoscopic image from which the surgeon must make a qualitative assessment of both the amount and location of astigmatism based upon distortion present in the keratoscopic image. The second class of devices quantitates corneal power at a chosen meridian and providing the surgeon with either an analogue or digital readout. Usually it is up to the surgeon to identify the meridian of greatest corneal power based on qualitative alterations of the keratoscopic image. These keratoscopes are based either on the optical principles of the von Helmholtz keratometer, or on nonparallel electronic image digitization. In this article we critically review commercially available surgical keratometers emphasizing their attributes and limitations. [Refractive and Corneal Surgery 1989;6:409-413].
Stability of Refraction During Two Years After Myopic Epikeratoplasty
Authors: Goosey John D , Prager Thomas C , Goosey Claire B , Allison Mark E , Marvelli Thomas L
Published: April 2021

ABSTRACT: A series of 54 consecutive myopic epikeratoplasty procedures was performed by three surgeons between November ?986 and August 1987. To evaluate the stability of the myopic epikeratoplasty procedure, this study was limited to the 33 eyes that had data 24 months after surgery. One year after surgery, 68% (19/28 eyes) had 20/40 or better uncorrected visual acuity and after two years, 57% (17/30 eyes) had 20/40 or better uncorrected visual acuity. Significant loss of surgical effect (increasing myopia) did not occur during the first six postoperative months (r=0.09, P = NS). This was due to the large amount of variability in spherical equivalent refraction during this interval. However significant regression was detected between 6 and 12 months after surgery (r=0.27, F = 4.74, P = 0.03). Even though there was further reduction in variability from 12 to 24 months, significant regression was not found (r = 0.07, P = NS). This suggests stabilization of refraction by approximately 12 months for this population. [Refractive and Corneal Surgery 1990;6:4-8]
Corneal Flattening by Shallow Circular Trephination in Human Eye Bank Eyes
Authors: Gilbert Michael L , Roth Allen S , Friedlander Miles H
Published: April 2021

ABSTRACT: Recent reports documenting central keratometric changes after removal of failed epikeratoplasty lenticules, compared to preoperative keratometry measurements, suggest that the annular corneal wound alters corneal curvature. Central corneal steepening has also been reported following circular and hexagonal keratotomy. We performed standard epikeratoplasty trephination with a Hessburg-Barron suction trephine followed by a peripheral lamellar spreading keratotomy on seven human eye bank eyes to determine the effect of these incisions on corneal topography.

In seven human eye bank eyes, the mean acute central keratometric flattening from the shallow trephine incision was 2.81 D (SD 2.28, P = .017), with no significant change in keratometry due to peripheral lamellar spreading (P= .916). Computerized numeric and three-dimensional graphic analysis of the keratographs demonstrated this central topographic flattening. Further studies are needed to investigate the reversibility of host corneal changes induced by epikeratoplasty procedures. [Refractive and Corneal Surgery 1990; 6:113-116.]
Myopic Excimer Laser Photorefractive Keratectomy: An Analysis of Clinical Correlations
Authors: Liu James C , McDonald Marguerite B , Varnell Ray , Andrade Helia Angotti
Published: April 2021

ABSTRACT: In this study, we examined the correlations among various factors that may affect the results of central photorefractive keratectomy for myopia. Data analyzed from our studies of blind, partially sighted, and normally sighted eyes included patient age, attempted correction, time to re-epithelialization, postoperative corneal clarity, refraction (relative spherical equivalent), and uncorrected visual acuity. We found that larger attempted corrections resulted in less accurate refractions and poorer uncorrected visual acuity. Older patients tended to have better results than younger patients, regardless of the amount of attempted correction. The relationship between the amount of attempted correction and corneal clarity was weak. There was a statistical correlation between corneal clarity scores and uncorrected visual acuity, but the range of corneal clarity scores was small and even the highest scores were probably not in the range that interfered with vision, so the relationship was probably not causal. The rate of epithelial healing did not appear to affect either refractive or visual results, and was not affected by patient age. These findings may be useful in guiding future efforts to improve the results of this new surgical procedure for the correction of refractive error. [Refractive and Corneal Surgery 1990;6:321-328.]
Evaluation of an Opacity Lensometer for Determining Corneal Clarity Following Excimer Laser Photoablation
Authors: Andrade Helia Angotti , McDonald Marguerite B , Liu James C , Abdelmegeed Mohamed , Varnell Ray , Sunderland Granger
Published: April 2021

ABSTRACT: The appearance of haze in the central cornea following photoablation with a 193 nm excimer laser is an important factor in the postoperative course of this procedure. Data from 37 human eyes treated with photorefractive keratectomy, 4 eyes treated with phototherapeutic keratectomy, and 5 untreated eyes were used to evaluate the ability of a commercially available opacity lensometer to provide an objective measure of corneal clarity. We found that the opacity lensometer was able to detect light scattered from the cornea but was not sufficiently sensitive to distinguish reliably among excimer-treated eyes with degrees of corneal haze evaluated as clear, trace, or 1+ by slit-lamp microscope examination. In untreated, clear corneas, the values obtained with the opacity lensometer in eyes measured with and without a clear contact lens were within one unit of each other for any given eye, but values from eye to eye varied over a range of six units. In a test simulating different amounts of corneal haze using contact lenses evenly coated with nail polish enamel, the log-transformed opacity lensometer values varied directly with percent light scattering as determined by spectrophotometry. These results suggest that the opacity lensometer measurements are reliable and reproducible, but that in the human cornea something is being measured by the opacity lensometer that is not taken into account in clinical slit-lamp microscope evaluation. Overall, it appears that, in its present form, this instrument is not useful to measure corneal clarity after excimer laser photoablation. [Refractive and Corneal Surgery 1990;6:346-351.]
Eight Years Experience With Permalens® Intracorneal Lenses in Nonhuman Primates
Authors: Werblin Theodore P , Peiffer Robert L , Binder Perry S , McCarey Bernard E , Patel Anil S
Published: April 2021

ABSTRACT

Background: For the past 8 years, three independent laboratories have been researching the biocompatibility and performance of Permalens® intracorneal lens implants in the corneas of nonhuman primates. Both myopic and hyperopic corrections have been achieved. This article describes the evolution of the intracorneal lens design and manufacturing process.

Methods: During this time period, 63 surgeries were performed on various species of nonhuman primates. Follow-up examination extended between 30 months and 8.2 years. Objective measures of refractive performance, as well as biocompatibility were made using slit lamp, retinoscopy, autorefractor, specular microscope, etc. Additionally, histopathology was performed on many of the specimens, both acute and chronic.

Results: Surgically successful implants were achieved in between 60% and 100% of eyes in the various series of lens implants outlined in the article. Levels of contamination in the preparation of hydrogels were felt to be responsible for many of the surgical failures. The removal of silicone and other contaminants seems to have significantly improved the biocompatibility of these materials within the cornea. The major histopathological finding was that there appeared to be some epithelial thinning over the implants, but in general excellent biocompatibility was obtained over the 8-year period outlined in this paper.

Conclusions: Although extensive studies of biocompatibility have been completed, the future of the performance of these materials remains to be proven in the human subject. Additionally, empirical relationships between lens implant power and refractive results will have to be determined in humans, prior to their general clinical usage. (Refract Corneal Surg 1992;8:12-22.)
Initial Human Experience With Permalens® Myopic Hydrogel Intracorneal Lens Implants
Authors: Werblin Theodore P , Patel Anil S , Barraquer Jose I
Published: April 2021

ABSTRACT

Background: Previous nonhuman primate experimentation has demonstrated the successful use of Permalens® hydrogel intracorneal lens implants for the correction of hyperopic and myopic refractive errors. This article documents the first human experience with myopic Permalens hydrogel intracorneal lens implants.

Methods: In this article, we report an 18-month follow up on five patients implanted with minus power hydrogel intracorneal lenses. All surgery and follow-up examinations were performed in Bogota, Columbia. The mean preoperative spherical refraction was - 14.00 ± 5.00 diopters (range, -9.5 to -19.00 D).

Results: Corrections of up to 13.00 D were achieved. Corrections deviated from the predicted correction by a mean of -5.00 ± 2.10 D (range, -2.80 to -8.00 D). No significant surgical or postoperative complications were noted. Visual recovery was rapid, usually achieving maximum acuity within 1 month.

Conclusions: Successful myopic refractive changes were accomplished in all five human subjects. The major problem with the study to date has been a significant undercorrection of the preoperative refraction. We anticipate that further empirically derived relationships between hydrogel lens power and refractive change will allow a more accurate prediction of refractive result. Also, the ability to surgically interchange myopic hydrogel inlays should allow correction of any residual refractive errors. Refract Corneal Surg 1992;8:23-26.)
Results of Transverse Keratotomies for Astigmatism After Penetrating Keratoplasty: A Retrospective Study of 48 Consecutive Cases
Authors: Saragoussi Jean-Jacques , Abenhaim Alain , Waked Naji , Koster Harry R , Pouliquen Yves J M
Published: April 2021

ABSTRACT

Background: High astigmatism is still a common complication of penetrating keratoplasty which often limits the final corrected visual acuity. Surgical correction of high astigmatism persistent after suture removal remains rather controversial. In our present study, we used the technique of transverse keratotomies for the surgical correction of high astigmatism following penetrating keratoplasty because of its simplicity and corrective potential.

Methods: We present a retrospective clinical study based on the results of 48 consecutive transverse keratotomy procedures performed on the graft. Three eyes were operated on twice, for a total of 51 procedures. The astigmatism had to be stable for at least 6 months after suture removal, with poor corrected visual acuity with spectacles or contact lenses. The operative protocol (number of incisions, optical zone size) was decided based on the degree of astigmatism. The mean postoperative observation period was 5.11 ± 3.93 months (range, 1 to 24 months).

Results: The mean preoperative cylinder was 8.96 ± 2.22 diopters and 4.91 ± 1.79 D postoperatively. The mean cylindrical change was 4.51 ± 2.77 D. The spherical equivalent remained unchanged in most cases. In a majority of cases, the corrected visual acuity for distance and near vision was improved. No cases of persistent graft edema caused by immunologic rejection or endothelial failure were observed. Moreover, in no case was there worsening of the best corrected visual acuity.

Conclusions: The technique of transverse incisions in the graft to correct or reduce high postkeratoplasty astigmatism is simple, efficient, and relatively safe. The main problem was poor predictability. (Refract Corneal Surg 1992;8:33-38.)
Numerical Modeling of Radial, Astigmatic, and Hexagonal Keratotomy
Authors: Pinsky Peter M , Datye Deepak V
Published: April 2021

ABSTRACT

Background: A mechanical model of the human cornea is proposed and employed in a finite element formulation for simulating the effects of keratotomy on the cornea.

Methods: The formulation assumes that the structural behavior of the cornea is governed by the properties of the stroma which is modeled as a thick membrane. The tensile forces in the cornea are resisted by the collagen fibrils embedded in the ground substance of the stromal lamellae. When the stromal lamellae are cut, as in keratotomy, it is assumed that they no longer carry any tensile forces, and the forces in the cornea are then resisted only by the remaining uncut lamellae. A constitutive model, which represents the anisotropy and inhomogeneity in the membrane rigidity induced by the incisions, has been employed in a geometrically nonlinear finite element membrane formulation for small strains with moderate rotations. This preliminary model is restricted to linear material behavior with no time dependency.

Results: A number of numerical examples are presented to illustrate the effectiveness of the proposed constitutive model and the finite element formulation for computing the immediate postoperative shift in corneal power resulting from radial, astigmatic, and hexagonal keratotomy. Surgical changes computed using the proposed model compare well with surgical corrections predicted by expert surgeons.

Conclusions: The proposed computational model of the cornea and the effects of sugical procedures on it is based on a number of important simplifying assumptions regarding the mechanical properties and structure of the corneal tissue at the ultrastructure level. The encouraging results found with present model suggest that further development and refinement will be useful. (Refract Corneal Surg 1992;8:164-172.)
On the Computer-Aided and Optimal Design of Keratorefractive Surgery
Authors: Velinsky Steven A , Bryant Michael R
Published: April 2021

ABSTRACT

Background: Several recent papers have discussed the use of engineering-based computer methods for the analysis of keratorefractive surgical procedures. What has been lacking is a broader view of the role of engineering analysis in keratorefractive surgery. This article demonstrates how these various analysis methods can be coupled to provide a comprehensive methodology for the design of refractive surgical procedures.

Methods: A structural model of the eye, based on a linearly elastic, transversely isotropic finite element formulation is coupled to a full-eye optical model. The optical errors due to refractive keratotomy are estimated by ray tracing through the optical model and measuring the position of the resulting focal plane relative to the retina. Computer-based optimization methods are employed to determine the surgical parameters necessary to correct myopia for a given set of surgical design goals.

Results: Results based on a hypothetical eye demonstrate agreement with clinical trends. Radial keratotomies are designed that eliminate refractive error while minimizing invasiveness in one case and maximizing the optical zone size in another. It is also shown that there is significant potential to customize this process on a patient-by-patient basis using clinically measured data.

Conclusions: We present an overview of the research necessary to bring this approach to fruition. While only a first step, the methodology presented in this article has the potential to increase the predictability of keratorefractive surgery by substantially increasing both the quality and the quantity of the information available to the refractive surgeon preoperatively. (Refract Corneal Surg 1992;8:173-182.)
A Thin-Shell Model of the Cornea and Its Application to Corneal Surgery
Authors: Howland Howard C , Rand Richard H , Lubkin Sharon R
Published: April 2021

ABSTRACT

Background: We present a thin-shell, analytical model of the vertebrate cornea to study the changes in shape resulting from surgical operations (eg, radial keratotomy).

Methods: A simple closed-form solution is derived for a thin linearly elastic spherical model of the cornea. We assume that the shell is symmetrical about a central axis and that the modulus of elasticity is the same in all directions. The surgery is modeled by allowing the modulus of elasticity (or equivalents the thickness) of the shell to depend upon position, measured as an angle from the axis of symmetry.

Results: The analytical nature of the solution allows us to compute the principal curvatures of the cornea explicitly. For example, for representative parameters, the model predicts the average corneal curvature changes from about 43 diopters before keratotomy to about 38 D after keratotomy.

Conclusions: The model is used to estimate Young's modulus from experimental data reported previously by Thomas et al (Invest Ophthalmol Vis Sci 1991;32:1000), as well as to investigate the effect of surgery on corneal flattening and the associated sensitivity to intraocular pressure changes. (Refract Corneal Surg 1992;8:183-186.)
A Comparison of Corneal Stromal Edema Induced From the Anterior or the Posterior Surface*
Authors: Cristol Stephen M , Edelhauser Henry F , Lynn Michael J
Published: April 2021

ABSTRACT

BACKGROUND: Many differences between the anterior and posterior corneal stroma have been reported. The physiological and mechanical properties of the cornea are a summation of these properties across each of the corneal regions. This article investigates corneal stromal swelling that is experimentally induced through each surface.

METHODS: Corneal stromal swelling was induced in human and rabbit corneas through either the anterior or posterior surface. The rate of stromal swelling was analyzed with a linear regression model.

RESULTS: Swelling in the rabbit stroma was 3.65 × faster when induced through the posterior surface than through the anterior surface (p < .0001), while the human stroma swelled 13.1 × faster through the posterior surface (p < .0001). The hydration of the stroma increased during swelling through the posterior surface, but paradoxically decreased during swelling through the anterior surface.

CONCLUSIONS: These experiments showed that stromal swelling occurs more rapidly through the posterior corneal surface than through the anterior surface. These results may have implications for the refractive surgeon performing laser ablative procedures on the anterior surface of the cornea. Refract Corneal Surg 1992;8:224-229.)
Report on Psychosocial Findings and Satisfaction Among Patients 1 Year After Excimer Laser Photorefractive Keratectomy
Authors: Kahle Gunther , Seiler Theo , Wollensak Josef
Published: April 2021

ABSTRACT

BACKGROUND: The first 26 patients who underwent photorefractive keratectomy with an excimer laser in our clinic with a 1-year follow up voluntarily answered a questionnaire.

METHODS: It was intended to get information about their social status, motivation, expectations, and satisfaction with myopic excimer laser photorefractive keratectomy.

RESULTS: All patients wore corrective lenses before surgery; 74% wore no optical correction after the photorefractive keratectomy. "To improve general vision" was the highest ranked motivation while "looking better" was only of minor importance. Seventy-two percent reported that their subjective vision became better; 28% felt that it didn't change, but none reported deterioration of subjective vision. Seventy-five percent of the patients reported improvement of their lifestyle after surgery, whereas 21% reported no change and one patient stated that his lifestyle got worse. On a scale ranging from 1 to 5, early postoperative course was painful with a mean score of 2.25; the treatment itself was considered as professional (1.42 ± 0.8) and well done (1.54 ± 0.8). Eighty-four percent of the patients reported that they were satisfied with the overall results.

CONCLUSIONS: All patients would decide again to have photorefractive keratectomy for myopic correction. [Refract Corneal Surg 1992;8:286-289.)
Facilitation of Ab Interno Radial Keratotomy by Air Keratoplasty
Authors: Mansour A M
Published: April 2021

ABSTRACT

BACKGROUND: Ab interno radial keratotomy is a keratorefractive procedure with radial incisions made by externalizing a blade inserted in the deep stroma. A major limitation of the procedure is the technical inability to establish a safe preDescemetic stromal entry of the blade with subsequent suboptimal depth of the radial incisions. A technique to delineate Descemet's membrane was investigated to obtain deeper incisions with the ab interno radial keratotomy.

METHODS: Air was injected with a 30-gauge needle mounted on a 3-milliliter syringe and entering the deep stroma at the limbus in human donor eyes. The injection was done in a pulse fashion with the needle tip advanced 3 mm away from the limbus. Ab interno radial keratotomy was then performed with and without air injection.

RESULTS: Bubbles were localized to the preDescemet region. The depth of the radial keratotomy incisions increased from 57.7% (SD = 1 1 .5%) without air injection, to 83.0% (SD = 10.6%) with air injection.

CONCLUSIONS: Deep stromal air injection delineates the pre- Descemet space, allowing deeper radial incisions with the ab interno radial keratotomy. [Refract Corneal Surg 1992;8:385-388.)
Circumferential Block Resection to Reduce Myopia
Authors: Buzard Kurt A
Published: April 2021

ABSTRACT

BACKGROUND: The surgical treatment of excessive myopia following penetrating keratoplasty has been largely ignored. Oversized corneal grafts can induce myopia and the Troutman wedge (block) resection has been used to correct astigmatism by removing tissue in a single corneal semimeridian. This study explores the use of block resections in opposing semimeridians to reduce myopia caused by a steep cornea.

METHODS: Six eyes received three different operations. One eye received 60-degree block resections in semimeridians located 90° (procedure 1), two eyes received 0.5-millimeter semicircumferential (180°) block resections (procedure 2), and three eyes underwent 0.5-millimeter 360degree circumferential block resections (procedure 3). All patients were followed for at least 1 year.

RESULTS: Procedure 1 (two 60-degree block resections) developed approximately 2.75 D of myopic correction at 1 year. The average reduction of spherical equivalent was 4.50 D for procedure 2 (one 180-degree block resection) and 10.50 D for procedure 3 (one 360-degree block resection) at 1 year. Although all eyes regained best spectacle-corrected visual acuity, the postoperative course was prolonged by irregular astigmatism.

CONCLUSIONS: Circumferential and semicircumferential block resections can reduce myopia after penetrating keratoplasty and in naturallyoccurring myopia, but the postoperative course can be prolonged, especially because of irregular astigmatism. Early removal of sutures results in regression of myopic correction. Refract Corneal Surg 1993;9:283-292.)
Intraoperative Intraocular Endoscopy in Transscleral Suture Fixation of Posterior Chamber Lenses: Consequences for Suture Technique, Implantation Procedure, and Choice of PCL Design
Authors: Althaus Christoph , Sundmacher Rainer
Published: April 2021

ABSTRACT

BACKGROUND: Transscleral suture fixation of posterior chamber lenses (PCLs) in the absence of capsular support causes minimal long-term alteration of the blood-aqueous barrier, if two requirements are fulfilled: 1) the transscleral suture has to penetrate exactly through the ciliary sulcus, and 2) the PCL haptics have to be directed into the sulcus and secured there.

METHODS: The surgical results of our standard techniques were controlled intraoperative^ by means of intraocular endoscopy in every patient since May 1991. Different alterations were necessary to improve the incidence of sulcus penetration and implantation.

RESULTS: With our conventional suture techniques, the needle penetrated the ciliary processes in the majority of eyes. Best results were achieved by passing the needle from the outside into the eye before opening the globe. When the eye was already hypotonic, the ciliary processes tended to prolapse in front of the needle tip, resulting in pars plicata fixation. With perforating keratoplasty, passing the needle from the inside out by feeling one's way into the sulcus with the needle tip gave good results. Even correct needle penetration through the sulcus did not guarantee correct positioning of the PCL haptics in the sulcus.

CONCLUSIONS: Selecting a suitable PCL design and a new implantation technique which reduces the angle of PCL implantation, the rate of correctly positioned PCLs in transscleral suture fixation is increased considerably. Refract Corneal Surg 1993;9:333-339.)

RÉSUMÉ

INTRODUCTION: La fixation des lentilles intraoculaires de chambre postérieure avec des sutures trans-sclérales, sans l'appui capsulaire, entraine très peu de changement de la barrière sang-aqueuse à condition que 1) la suture transsclérale pénètre exactement dans le sulcus ciliaire et 2) que les anses soient dirigées dans le sulcus et y être suturées.

MÉTHODES: Nos techniques chirurgicales furent contrôlées pendant l'opération par endoscopie intra-oculaire chez chaque patient depuis mai, 1991. Plusieurs changements furent nécessaires afin d'améliorer l'incidence de pénétration et d'implantation dans le sulcus ciliaire.
Arcuate Keratotomy for the Correction of Spherical Hyperopia in Human Cadaver Eyes
Authors: Vrabec Michael P , Durrie Daniel S , Hunkeler John D
Published: April 2021

ABSTRACT

BACKGROUND: A new experimental surgical technique to correct spherical hyperopia by steepening of the central corneal curvature was performed on human cadaver eyes.

METHODS: Ten eyes were used in the study. All were pretreated with glycerin to ensure a uniform corneal thickness between .55 and .65 mm on ultrasonic pachometry. A constant intraocular pressure of approximately 30 to 40 mm Hg was maintained in each eye by the injection of saline into the vitreous cavity. This was verified by pneumotonometry. A vertical blade diamond knife was set at 100% of the thinnest of four paracentral readings. Each eye underwent preoperative computed topography. One set of five eyes had 12 incisions made following a 5.75-millimeter diameter Mendez hexagonal marker that included unconnected T incisions at each junction (ie, "Hex T" pattern). The other set of five eyes had four arcuate incisions made following a 6-millimeter diameter zone marker; each incision was 60° in arc. Immediately after surgery, computed topography was repeated.

RESULTS: The hexagonal keratotomy set of eyes had an average steepening of the cornea of 0.80 D with a range of -1.05 to +4.38 D. The arcuate keratotomy set had an average steepening of +2.12 D with a range of + 1.27 to +3.27 D.

CONCLUSIONS: This study suggests arcuate keratotomy may be a more effective procedure in the correction of spherical hyperopia when compared with hexagonal keratotomy. The amount of corneal steepening achieved in a cadaver eye model may not be the same as when performed in vivo. (Refract Corneal Surg 1993;9:388-391.)