Abstract
Purpose: :
To determine if the Scotopic Pupil Size and/or the Level of Pre–Operative Myopia can be used to predict the Severity of Starburst Phenomenon following LASER Vision Correction
Methods: :
A Series of 134 Conventional Surface Ablation Procedures (including LASEK, PRK and Epi–LASIK) were studied with the Larson Glarometer device to quantify the level of post–operative Scotopic Starburst Phenomenon. All procedures performed by the same surgeon (WT). All LASER Ablations performed on the same VISX S3 LASER using Conventional (Non–Wave Front) Treatments with 6.5 mm Optical Zones and 8 mm Blend Zones. Post–op patients were placed in a scotopic room and asked to look at the Larson glarometer, a black box with two 4mm LED lights. Patients were asked to compare their post–op starbursts with a chart displaying starbursts with diameters of 5,10 and 15mm. All reported Glarometer measurements were taken with the patient's best spectacle correction in place (if any). Each eye was tested separately. All patients were at least 3 months post–operative, with BCVA of 20/25, or better.
Results: :
Multiple Linear Regression Analysis demonstrated a notable correlation between Scotopic Pupil Size and Post–Operative Starburst Radius (partial r = .64, p < .0005). The correlation between the Level of Pre–Operative Myopia (Spherical Equivalent) and Post–Operative Starburst Radius was lower, but statistically significant (partial r = .32, p < .0005). After accounting for the above two variables on Starburst Radius, the analysis revealed a significant post–operative pupil size by myopia interaction, partial r = .35, p < .0005. Collectively, these three factors accounted for an adjusted 53% of the variance in starburst radius, corresponding to a multiple correlation of .73, F (3, 130) = 51.11, p < .0005. Also, preop pupil size correlates to post–op pupil size by only .746 using the Pearson correlation method.
Conclusions: :
Despite previous studies that have suggested no correlation exists between Pre–Operative Pupil Size and Post–Operative Scotopic Symptoms following LASIK, our study clearly found otherwise. This study utilized a new device (Larson Glarometer) which quantifies a patient's Scotopic Starburst Phenomenon. The size of the postoperative starburst radius was correlated with both scotopic pupil size and degree of preoperative myopia. Predicting post–op pupil size based on preop measurements is more difficult and requires further investigation
Keywords: refractive surgery • refractive surgery: PRK • refractive surgery: optical quality