bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photorefractive Keratectomy and Laser In Situ Keratomileusis for Myopia Between 6.00 and 10.00 Diopters
Authors: Helmy Sherif A , Salah Ayman , Badawy Tarek T , Sidky Ahmed N 
Published: April 2021

ABSTRACT
BACKGROUND: Excimer laser photorefractive keratectomy (PRK) can be effective in correcting myopia up to -6.00 diopters (D). Between -6.00 D and *10.00 D, the procedure is considered less effective and safe because it has been associated with dense scar formation and a high rate of regression. We compared photorefractive keratectomy (PRK) in this group of myopes with excimer laser keratomileusis in situ (LASIK).
METHODS: Forty consecutive eyes with a manifest refraction between -6.00 and -10.00 D were treated with PRK using an ablation-zone diameter of 6 mm. Subsequently, 40 consecutive eyes were treated with LASIK under a hinged flap using an ablation-zone diameter of 5 mm. All procedures used a Summit OmniMed laser and were done by the same surgeon.
RESULTS: Preoperatively, 24 eyes (60%) undergoing PRK had 20/20 spectacle-corrected visual acuity; 1 year postoperatively, 20 (50%) had 20/20 vision uncorrected. Preoperatively, 13 eyes (33%) undergoing LASIK had 20/20 spectacle-corrected visual acuity; 1 year postoperatively, 24 (60%) could see 20/20 uncorrected. Sixteen (39%) PRK eyes had a spherical equivalent refraction within +1.00 D at 1 year; 20 (60%) eyes undergoing LASIK had a refraction within +1.00 D at that point. None of the eyes treated with LASIK developed corneal haze, while after PRK, 36 eyes (90%) developed haze (23 eyes [57%] +2 to +3).
CONCLUSION: LASLK under a hinged flap proved superior to PRK in treating myopia between -6.00 D and -10.00 D. [J Refract Surg. 1996;12:417-421.]
Laser In Situ Keratomileusis to Correct Myopia of -6.00 to -29.00 Diopters
Authors: Knorz Michael C , Liermann Andreas , Seiberth Volker , Steiner Holger , Wiesinger Bettina 
Published: April 2021

ABSTRACT
BACKGROUND: Photorefractive keratectomy eau cause corneal scarring and visual loss in highly myopic eyes. We evaluated laser in situ keratomileusis (LASIK) because it has the theoretical advantage of preserving both the corneal epithelium and Bowman's layer.
METHODS: In a prospective study, LASIK was performed in 62 myopic eyes (42 patients) using the Automatic Corneal Shaper (Chiron Vision) and the Eeracor 116 excimer laser (Chiron Technolas). We measured refraction and visual acuity, and evaluated corneal topography (TMS 1) and corneal clarity after 4 to 8 weeks and 4 to 6 months.
RESULTS: Four- to 6-month follow up was completed in 51 eyes. The mean preoperative spherical equivalent refraction was -14.80 diopters (D) (range, -6.00 to -29.00 D). Postoperatively, the mean deviation from the target refraction was -1.70 D (range, -9.00 to +2.50 D) at 4 to 8 weeks and -1.90 D (range, -9.50 to 4-2.25 D) at 4 to 6 months. At 4 to 6 months, 19 eyes (37%) were within ±0.50 D of the target refraction, 24 (47%) within ±1.00 D, 33 (65%) within ±2.00 D, and 40 (78%) within ±3.00 D. From 4 to 8 weeks to 4 to 6 months, the mean regression of myopia was -0.20 D (0.50 D or less in 24 eyes [47%], 1.00 D or less in 32 [63%], and 2.00 D or less in 42 [82%]). In six eyes (12%), the stromal interface was not visible, in 38 (74%) it was barely visible, and in seven (14%) it was clearly visible. Corneal topography revealed only small variations in clear-zone gize and dioptric value, demonstrating a very stable correction 4 to 6 months postoperatively.
CONCLUSIONS: LASIK may be a safe and effective procedure to correct high myopia. Further research is required to develop satisfactory microkeratome technology, effective laser algorithms, and to determine long-term stability of refraction. [J Refract Surg. 1996;12:575-584.]
Comparison of Intersecting Trapezoidal Keratotomy and Arcuate Transverse Keratotomy in the Correction of High Astigmatism
Authors: Harto Miguel A , Maldonado Miguel J , Cisneros Angel L , Perez-Torregrosa Vicente T , Menezo José L 
Published: April 2021

ABSTRACT
BACKGROUND: High astigmatism can be corrected using trapezoidal or arcuate transverse keratotomies. Videokeratography enables qualitative evaluation of the corneal topography.
METHODS: Fifty-five eyes of 41 patients presenting with high astigmatism after penetrating keratoplasty or naturally occurring astigmatism (mean, 6.29 diopters [D]; range, 3.00 to 16.00 D) underwent correction using either intersecting trapezoidal or arcuate transverse keratotomies. Corneal topographic maps were analyzed and classified into keratographic patterns. Mean follow up was 3 years (range, 1 to 6 years).
RESULTS: The mean net decrease in refractive astigmatism was 3.60 D (52.7% reduction). The flattening/steepening ratio was on average higher for intersecting trapezoidal keratotomy (7.26 for astigmatism after penetrating keratoplasty and 8.31 for naturally occurring astigmatism) than for arcuate transverse keratotomy (.98 in astigmatism after penetrating keratoplasty and 1.76 in naturally occurring astigmatism). Accordingly, intersecting trapezoidal keratotomy tended to produce a hyperopic shift in the spherical equivalent refraction, whereas arcuate transverse keratotomy generally preserved the spherical equivalent refraction (mean hyperopic shift, 2.65 and .56 D, respectively). The mean vector-corrected change of refractive astigmatism after intersecting trapezoidal keratotomy was 88.8% in naturally occurring (ra=21 eyes) and 70.3% in penetrating keratoplasty astigmatism (n= 13). Arcuate transverse incisions corrected on average 79.9% of naturally occurring (n=13) and 60.8% of penetrating keratoplasty astigmatism (w=8). Videokeratography showed the asymmetric bowtie pattern as the most frequent pattern for both procedures. Intersecting trapezoidal keratotomy was characterized by relatively higher incidences of polygonal and irregular patterns. Arcuate transverse incisions caused less wound healing defects and glare than intersecting trapezoidal keratotomy.
CONCLUSIONS: Both intersecting trapezoidal keratotomy and arcuate transverse incisions effectively reduced high naturally occurring astigmatism and astigmatism after penetrating keratoplasty. However, greater corneal surface irregularity and more complications were seen following intersecting trapezoidal keratotomy. Trapezoidal keratotomy should not be used unless a large decrease of myopia is needed, and then a nonintersecting technique is preferable. [J Refract Surg. 1995;12:585-594.]
Inferior Steepening is Associated with Thinning of the Inferotemporal Cornea
Authors: Colin Joseph , Sale Yves , Malet Florence , Cochener Beatrice 
Published: April 2021

ABSTRACT
PURPOSE: Videokeratography has enabled detection of inferior steepening patterns in patients thereby designated as keratoconus suspects. Since no information about the corneal thickness of these eyes is available, we studied several patients with such patterns, and compared the corneal thickness of their eyes with that of normals.
METHODS: Three groups of patients who had undergone videokeratography were studied with ultrasonic pachymetry centrally and in four quadrants at the 3-mm clear zone: 44 eyes with true keratoconus, 23 eyes of individuals with inferior steepening of the cornea who were family members of patients with keratoconus; and 44 normal eyes never fitted with contact lenses. The corneal thickness of the eyes in the first two groups was then compared with that in the third using ANOVA and Student's t test.
RESULTS: Corneal thickness in the normal eyes and in those with inferior steepening was similar in all except the inferotemporal quadrant. In this quadrant, the corneas of the eyes with inferior steepening were thinner than those of the normal eyes: 544 ± 32 µm vs 581 ± 30 µm (p < .05)
CONCLUSION: Eyes with inferior steepening on videokeratography have thinner inferotemporal corneas than normal eyes. [J Refract Surg. 1996;12:697-699.]
Variability in Corneal Thickness Before, During, and After Radial Keratotomy
Authors: Terry Mark A , Ousley Paula J 
Published: April 2021

ABSTRACT
BACKGROUND: Precision in radial keratotomy requires accurate pachymetry for safety and efficacy. We evaluated the location, timing, and extent of changes in corneal thickness between those determined by preoperative measurement in the clinic and those determined by pre-incision and post-incision measurement in the operating room.
METHODS: Sixty eyes of 37 patients had ultrasonic pachymetry measurements of the central and paracentral cornea taken in the clinic 20 minutes before each patient underwent radial keratotomy. The pachymetry was repeated intraoperatively immediately before and, in a subset of 17 eyes, immediately after incisions were made, and the readings were compared.
RESULTS: The thinnest of the four paracentral readings measured just prior to placing the radial keratotomy incisions was located temporally in 92% of the eyes and inferiorly in 8%. Corneas progressively thinned from clinic to surgery by an average of 7 ± 12 µm centrally and 10 + 18 µm temporally. Additional thinning of 13 ± 14 µm centrally and 22 + 23 µm temporally occurred during surgery.
CONCLUSION: The thinnest paracentral corneal region measured in an eye was not always located in the same quadrant preoperatively and intraoperatively. During the time of incision placement, significant corneal thinning had occurred at each incision site. Individual variations in corneal thickness between that measured preoperatively and that measured during surgery cautions against the use of clinic readings for diamond knife settings during radial keratotomy. [J Refract Surg. 1996;12:700-704.]
Hot Needle Thermal Keratoplasty to Correct Naturally Occurring Hyperopic Astigmatism
Authors: Charpentier Dominique Y , Bertel Franck , Duplessix Michel , Colin Joseph , Denis Philippe 
Published: April 2021

ABSTRACT
OBJECTIVE: To study the safety, effectiveness, predictability and stability of sectoral thermal keratoplasty in the treatment of naturally occurring hyperopic astigmatism.
METHODS: Using Fyodorov's technique, sectoral controlled coagulations were applied on both sides of the flattest meridian in 12 eyes from eight patients with naturally occurring hyperopic astigmatism. Preoperative average refractive cylinder was +3,19 ± 1.13 diopters (D), and the mean spherical component was +0.71 ± 1.03 D. Mean follow-up time was 13.2 months.
RESULTS: Immediately after surgery, we observed a significant overcorrection in the treated meridian in all patients. Then, a gradual decrease of the refractive effect was noticed, since the average refractive astigmatism was +0.25 ± 1.23 D at 6 months and +1.15 ± 0.86 at 12 months after surgery. At 1 month after surgery, the mean shift in the cylinder axis was 83.75° ± 8.82° and 12.08° ± 12.33° at the 1-year examination. Uncorrected visual acuity was 20/40 or better in all patients 1 year after surgery. We did not observe severe corneal complications, such as irregular astigmatism or delayed epithelial wound healing.
CONCLUSION: Hot needle sectoral thermal keratoplasty appears to be safe and partially effective in reducing hyperopic astigmatism, but considerable postoperative regression may occur. [J Refract Surg 1996;12:705-708.]
Posterior Polymorphous Dystrophy Associated with Astigmatism and Amblyopia in Children
Authors: DeRespinis Patrick A , Norden Richard A , Rispoli Lauren C 
Published: April 2021

ABSTRACT
BACKGROUND: Posterior polymorphous dystrophy has been described in the scientific literature as having more than a casual association with keratoconus in adults. We studied four consecutive children with posterior polymorphous dystrophy who had coexisting astigmatism. In our patients, the posterior changes appeared to be associated with the corneal astigmatism, as evidenced by videokeratography.
METHODS: Four consecutive cases of posterior polymorphous dystrophy in children were found over a 3-year period by one of the authors (PD). They presented with varying degrees of amblyopia in the eyes with the greater amount of posterior polymorphous dystrophy. Cycloplegic refractions and keratometry readings were performed . The more affected eyes had greater degrees of astigmatism, presumably causing the amblyopia. Whenever possible, the results were supplemented by confirmation by a corneal specialist, specular microscopy, slit-lamp photographs and videokeratography.
RESULTS: Greater asymmetry of posterior polymorphous dystrophy was associated with greater astigmatism in the more affected eye. When more astigmatic anisometropia was present there was a greater amblyopia. Videokeratography of one of the patients showed that an area of confluent blebs forming a crescent shape compared exactly with a steep cylinder along the same axis. With-the-rule astigmatism was associated with a more diffuse pattern of blebs.
CONCLUSION: Decreases in visual acuity in children with posterior polymorphous dystrophy may sometimes be due to an amblyopia caused by the astigmatism of asymmetric disease. [J Refract Surg. 1996;12:709-714.]
Topography of Rabbit Corneas after Photorefractive Keratectomy for Hyperopia Using Airborne Rotational Masks
Authors: Dierick Hans G , Van Mellaert Catherine E , Missotten Luc 
Published: April 2021

ABSTRACT
PURPOSE: To determine the long-term outcome of photorefractive keratectomy (PRK) for hyperopia on the rabbit cornea using ablation profiles with a smooth transition zone.
METHODS: Two profiles were ablated by means of an excimer laser and rotational masks, each profile on four rabbit eyes. Corrections of +10 diopters (D) were planned in all operations. The right eye was treated with a 4-mm optical zone and a 2-mm transition zone (4-mm/8-mm profile), the left eye with a 4-mm ablation and a 1-mm transition zone (4mm/6-mm profile). Corneal topography was measured with an EyeSys videokeratoscope at 3, 10, 20, 30, 40, 50, 65, 75 and 120 weeks postoperatively.
RESULTS: After more than 2 years the axial power- not corrected for the physiologic flattening of the corneas- showed a residual steepening of +3.60 (± 3.90) D for the right eyes and +3.9 (±2.8) D for the left eyes. The diameter of the topographic optical zone was equal to or smaller than the innermost mire. The power started to decrease paracentrally, giving the profile graph of the power a characteristic peak pattern. The flat transition zone, typical of PRK for hyperopia, could be recognized on the Placido images as a characteristic broadening of the midperipheral rings. The axial power map and the power profile did not show this flattening in the transition zone.
CONCLUSION: A steepening of the central cornea by PRK is possible. The diameter of the topographic optical zone of homogeneous power is smaller than induced, increasing considerably the asphericity of the central cornea. The 4-mm/8-mm ablation profiles did not give a larger diameter topographic optical zone nor less regression than the 4-mm/6-mm ablation profiles. The videokeratoscope makes errors in measuring axial power of mixed convex-concave surfaces. [J Refract Surg 1996;12:774-782]
Laser in situ Keratomileusis for Myopia from -5.50 to -11.50 Diopters with Astigmatism
Authors: Zaldivar Roberto , Davidorf Jonathan M , Oscherow Susana 
Published: April 2021

ABSTRACT
PURPOSE: To determine the efficacy, predictability, safety, and short-term stability of laser in situ keratomileusis (LASIK) in treating patients with high myopia and astigmatism.
METHODS: We retrospectively studied the results of our initial 119 eyes with myopia ranging from -5.50 to -11.50 D and astigmatism less than 4.00 D that underwent LASIK with the Nidek EC-5000 excimer laser. Follow-up was at 1 day, 1 month, and 3 to 6 months; follow-up was 71% (84 eyes) at the 3 to 6 month visit (average 4.5 months).
RESULTS: Of the 84 eyes with 3 to 6 months of follow-up, mean baseline spherical equivalent refraction was -8.62 ± 1.27 D and mean cylinder was -1.84 ± 1.02 D. Mean postoperative spherical equivalent refraction at the last examination was -0.61 ± 0.84 D and mean cylinder was -0.39 ± 0.38 D, with 83% (70 eyes) achieving a spherical equivalent refraction within ±1.00 D of emmetropia, and 56% (47 eyes) within ±0.50 D. Mean regression of spherical equivalent from 1 day to 1 month was less than -0.50 D and refractions were stable between 1 month and 3 to 6 months. An uncorrected visual acuity of 20/40 or better was noted in 84% (71 eyes) of these eyes on day 1 after surgery, in 75% (63 eyes) at 1 month, and in 77% (65 eyes) at 3 to 6 months. Twenty-two percent (18 eyes) of these eyes achieved 20/20 or better uncorrected visual acuity at 3 to 6 months; only 17% (14 eyes) had 20/20 or better spectacle-corrected visual acuity before surgery. One patient lost two or more lines of spectacle-corrected visual acuity at the last examination due to epidemic keratoconjunctivitis.
CONCLUSION: LASIK with the Nidek EC-5000 excimer laser appears to be an effective and safe means for treating patients with high myopia and astigmatism. Studies with longer follow-up will help evaluate the long-term stability of the procedure and the possibility of late complications. [J Refract Surg 1998;14:19-251
Excimer Laser Photorefractive Keratectomy for Presbyopia: 24-month Follow-up in Three Eyes
Authors: Vinciguerra Paolo , Nizzola Guido Maria , Bailo Giorgio , Nizzola Francesco , Ascari Andrea , Epstein Daniel 
Published: April 2021

ABSTRACT
BACKGROUND: For some patients, standard optical correction for presbyopia is not satisfactory. Using a specially designed mask, we developed a procedure for correcting presbyopia with excimer laser photorefractive keratectomy (PRK).
METHODS: A mask consisting of a mobile diaphragm formed by two blunt blades was used to ablate a 10 to 17 µm deep semilunar-shaped zone immediately below the pupillary center, steepening the corneal curvature in that area. Three eyes of three presbyopic patients were treated, aiming at a near addition of +3.00 D. Follow-up time was 24 months.
RESULTS: After an initial regression of 1.00 D during the first 6 months, the presbyopic correction remained stable for the duration of the follow-up period, enabling uncorrected near vision of J3 in all three eyes. Uncorrected distance visual acuity was not altered. Contrast sensitivity (Regan) was slightly decreased only at the 11% level. Videokeratography confirmed corneal steepening in the ablated area.
CONCLUSION: The visual and refractive outcome of excimer laser PRK for presbyopia with the Aesculap-Meditec MEL 60 is promising, especially in view of the 2-year follow-up. [J Refract Surg 1998;14:31-37]
Effect of Decreasing Surface and Interface Irregularities after Photorefractive Keratectomy and Laser in situ Keratomileusis on Optical and Functional Outcomes
Authors: Vinciguerra Paolo , Azzolini Marco , Airaghi Pietro , Radice Paola , De Molfetta Vito 
Published: April 2021

ABSTRACT
PURPOSE: To assess a new method for decreasing corneal ablated surface irregularities after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) by performing a final smoothing immediately after the treatment.
METHODS: One hundred forty-seven eyes with ablation irregularities after PRK or LASIK using the Nidek EC-5000 excimer laser and examined with the Nidek EAS 1000, were randomized into two groups: 74 eyes had final smoothing and 73 eyes were patched immediately. Preoperative mean refraction for the smoothing group was -7.55 ± 250 D and for the patched group, it was -7.30 ± 1.90 D, (p = 0.04).
RESULTS: At 12 months after treatment, mean haze was 0.5 ± 0.3 in the smoothing group and 1.2 ± 0.4 in the patched group (p = 0.006); mean spectaclecorrected visual acuity was 1.1 ± 0.25 in the smoothing group and 0.95 ± 0.18 in the patched group (p = 0.02); the percentages of eyes within 1.00 D of the planned correction was 68% in the smoothing group and 33% in the patched group.
CONCLUSION: Performing a final smoothing immediately after PRK or LASIK improves refractive and optical outcomes. [J Refract Surg 1998;14:S199-S203]
Multizone and Transition Zone Photorefractive Keratectomy for High Myopia
Authors: Zhao Kanxing , Wang Yan , Zuo Tong , Wang Hongyue 
Published: April 2021

ABSTRACT
BACKGROUND: Variations in ablation profile may alter the stability of refraction and cause adverse effects in photorefractive keratectomy. We compared the benefits of multizone and transition zone ablation in the treatment of high and extreme myopia.
METHODS: A scanning excimer laser system, Nidek EC-5000 was used with three-zone treatment and our results were compared retrospectively with results obtained in a group with a conventional ablation profile using a transition zone.
RESULTS: Six-month follow-up data were available for 65 eyes with a transition zone and 46 eyes with three-zone treatment. Postoperative mean (±SD) healing time was 2.98 days (±0.12) and 3.02 days (±0.15), and night vision disturbances were 16% and 11.5% respectively, (p>0.05). Refractive regression was also similar in the two groups; uncorrected visual acuity of 20/40 or better was 90.77% and 89.14%. At 6 months postoperatively, the mean (±SD) corneal clarity score was 0.61 (±0.29) in the transition zone group, and 0.51 (±0.07) in the multizone group (p<0.05).
CONCLUSION: No discernible differences between treatments were found in either epithelial healing or refractive outcome, such as regression, between the groups. Corneal haze was less in eyes treated with three-zone ablation. [J Refract Surg 1998;14:S222-S225]
Photorefractive Keratectomy for Myopia with -8.00 Diopter Cylindrical Correction
Authors: Shah Sunil , Chatterjee Anupam 
Published: April 2021

ABSTRACT
PURPOSE: A colleague requested PRK. The last time the patient was seen, no spectacles or contact lenses were worn. However, subjective refraction was -7.00 -5.50 x 165°. The original Nidek nomogram would have suggested setting the laser at the actual refraction. Our algorithm adjustments suggested a 40% extra correction of cylinder would be required. The laser was therefore set to -3.50 -8.00 ? 165° aiming for a -1.00 -2.00 x 165° outcome to allow for possible retreatment.
METHODS: A 165 µm depth ablation was performed.
RESULTS AND CONCLUSION: At 6 weeks after surgery, visual acuity was 0.63 unaided with a refraction of +1.50 -1.75 x 170° on pred forte. [J Refract Surg 1998;14:S228-S229]
Posterior Chamber Phakic Intraocular Lens for Myopia of -8 to -19 Diopters
Authors: Zaldivar Roberto , Davidorf Jonathan M , Oscherow Susana 
Published: April 2021

ABSTRACT
PURPOSE: To examine the efficacy, predictability, stability, and safety of posterior chamber phakic intraocular lens (IOL) implantation in patients with extreme myopia.
METHODS: We analyzed the results of 124 eyes that received a posterior chamber hydrogel collagen plate phakic IOL (Staar Collamer Implantable Contact Lens, ICL) for the correction of their myopia. The target postoperative spherical equivalent refraction was emmetropia. Mean follow-up was 11 months (range 1 to 36 mo).
RESULTS: The mean preoperative spherical equivalent refraction was -13.38 ± 2.23 D (range, -8.50 to -18.63 D). Mean postoperative spherical equivalent refraction at last examination was -0.78 ± 0.87 D (range, +1.63 to -3.50 D), with 69% (86 eyes) within ±1.00 D and 44% (55 eyes) within ±0.50 D of emmetropia. The refraction remained stable with a statistically insignificant change (p > 0.05 at each interval) during follow-up. A gain of two or more lines of spectacle-corrected visual acuity was seen in 36% (45 eyes) at last examination. One eye (0.8%) lost two or more lines of spectacle-corrected visual acuity from a retinal detachment.
CONCLUSION: Posterior chamber phakic IOL implantation with the Staar Collamer plate lens is an effective and safe method for reducing or correcting myopia between -8 and -19 D. Gains in spectacle-corrected visual acuity were common, and results suggested good refractive stability. Improvements in phakic IOL power calculation formulas are needed to improve the predictability of refractive outcome. [J Refract Surg 1998;14:294-305]