Zhongshan Ophthalmic Center, Sun Yat-Sen University,China
Conditions: Limbal Dermoid
Sponsor: Zhongshan Ophthalmic Center, Sun Yat-sen University

Background and Objective(s):  
Keratoplasty, also known as corneal transplantation, is a surgical procedure in 
which a damaged or diseased cornea is replaced entirely (penetrating keratoplasty) or 
partially (lamellar keratoplasty) by a donated corneal graft. Post-keratoplasty 
astigmatism is multifactorial in its etiology, in which the preoperative factors involve 
the age and health of donor tissue, recipient pathology, the intraoperative factors 
include trephine quality, graft size, wound apposition and suturing technique and 
suture material and the postoperative factors cover wound healing, postoperative 
drugs, inflammation, corneal vascularization, rejection.  
The contrast sensitivity function (CSF) provides a comprehensive measure of the 
visual system which has been used to characterize spatial vision deficits in many 
visual disorders such as amblyopia, multiple sclerosis, glaucoma, retinitis pigmentosa, 
as well as autism spectrum disorder. Although some studies have reported the contrast 
sensitivity function of keratoplasty patients, few has documented the CSF in different 
spatial frequencies as well as its relationship between the life quality. To our 
knowledge, the current study would be the first case series to inquiry the contrast 
sensitivity function in the keratoplasty patients with quick CSF, as well the 
relationship between visual quality and life quality. 
 
Design:  
All participants would undergo an ophthalmic examination that included silt-lamp 
biomicroscopy，visual acuity, corneal topography, contrast sensitivity measurements, 
9-SF life quality questionnaire and fundus examination. Then the normal group would 
be covered by positive spherical lens of 1.0D to 6.0D to repress the BCVA to 0.1 to 
0.9 respectively to compare the visual functions with the keratoplasty patients on the 
same visual acuity. 
 
Methods: 
Subjects and Inclusion Criteria 

This observational, cross-sectional, non-consecutive case study would be 
conducted with patients who have accepted keratoplasty and healthy subjects who 
visited the Corneal Clinic of Zhongshan Ophthalmic Center, Guangzhou, China. The 
research was performed according to the tenets of the Declaration of Helsinki. The 
study protocol was approved by the Zhongshan Ophthalmic Ethical Committee. All 
subjects provided informed consent after receiving both written and verbal 
explanations of the nature and intent of the study. 
The Inclusion Criteria for keratoplasty patients are: 1) Accept the corneal 
transplantation based on the clinical diagnosis of ocular surface disease; 2) more than 
7 and less than 60 years old; 3) absence of other ocular disorders and no history of eye 
surgery and other systemic diseases. And the exclusion Criteria are: 1) less than 7 or 
more than 60 years old; 2) with the history of eye surgery and other systemic diseases. 
All participants underwent an ophthalmic examination that included silt-lamp 
biomicroscopy， visual acuity, corneal topography, contrast sensitivity measurements, 
9-SF life quality questionnaire and fundus examination. Then the normal group would 
be covered by positive spherical lens of 1.0D to 6.0D to repress the BCVA to 0.1 to 
0.9 respectively to compare the visual functions with the keratoplasty patients on the 
same visual acuity. 
 
CSF Measurements  
The quick CSF method, implemented in a 10 alternative forced-choice digit 
identification task, was used to assess the contrast sensitivity function34, 38. Stimuli 
were displayed on a gamma-corrected 46 inch LCD monitor (Model: NEC LCD P463) 
with a 1920×1080 pixel resolution, 50 cd/m2 mean luminance and 60 Hz vertical 
refresh rate. Observers viewed the display monocularly from a distance of 4 m in a 
dark room. For each trial, they were asked to verbally report the identities of three 
digits presented on the screen to the experimenter, who used the computer keyboard 
to enter their responses. The stimuli disappeared after all the responses were entered. 
Observers were given the option to report ‘‘I don’t know’’ upon which the response 

was coded as incorrect. No feedback was provided. All three responses were used to 
update the posterior distribution of the CSF parameters, which in turn was used to 
adaptively choose the most informative combination of spatial frequency and contrast 
for the next trial. A new trial started 500 ms after the responses. There were 30 trials 
in approximately 5 min. The quick CSF data were scored to generate the cutoff spatial 
frequency, defined as the spatial frequency corresponding to a perceptual sensitivity 
of 1, and the area under the log CSF (AULCSF), a summary measure of the window 
to spatial vision. 
 
Statistical Analysis Plan:  
Data would present as means ± standard deviations. Between group t-test would 
be used for statistical comparisons of the CSF results, including cutoff SF and 
AULCSF between the astigmatism group and the control group. A multiple linear 
regression analysis would be performed to investigate the relation between the 
AULCSF and the lens power of astigmatism. Statistical analyses were performed 
using SPSS version 17.0 (SPSS, Inc., Chicago, IL, USA), and p values of < 0.05 
would be considered statistically significant.