Distribution Of Angle Alpha And Angle Kappa Among Adult Candidates For Cataract Surgery

The current study aimed to describe the distribution of angle alpha and angle kappa as well as their associated ocular biometric parameters in a large population of candidates for cataract surgery.

A cross-sectional retrospective study. Included in this study were individuals referred for cataract surgery between February 2018 and January 2020, who were 18 years of age and older, and who had undergone ocular biometric evaluation by means of the IOLMaster 700 (Carl Zeiss Meditec, AG, Germany, software version: 1.80.6.60340.C75999).

This study included 8,119 eyes of 4,781 candidates for cataract surgery (mean age 70.7±12.9 years). There were 49.9% right eyes, and 53.0% patients were females. The angles and ocular biometric parameters were measured by the IOLMaster 700 (Carl Zeiss Meditec, AG, Germany).

Patient’s age and gender, and most of their ocular biometric measurements were similar for the right and left eyes except for pupil diameter (4.01±1.18 vs. 3.92±1.14 mm, respectively, P<0.001). The angle alpha magnitude was similar for both eyes (0.50±0.20 and 0.51±0.21 mm, P=0.08), whereas the angle kappa magnitude was greater in the right eyes (0.37±0.21 vs. 0.33±0.20 mm, P<0.001). The angle kappa magnitudes were greater in the right eyes compared to the left eyes for both males (0.36±0.21 vs. 0.33±0.21 mm, respectively, P<0.001) and females (0.37±0.20 vs. 0.34±0.20 mm, respectively, P<0.001). The magnitudes of both angles were positively correlated in both right and left eyes (r=0.64 and r=0.6, respectively, P<0.001 for both).

The present study documents that the magnitudes of both the angle alpha and angle kappa present significant variations according to gender, eye laterality, angle location, and biometric parameters, such as AL. It has been shown that these values are also population-specific. Due to the importance of angle alpha and angle kappa for the satisfaction of patients after modern cataract and refractive surgery, understanding and subclassifying these angles may improve patient selection and aid in choosing the most suitable personalized treatment options. Possible implications, such as refinement of objective identification of the dominant eye in monovision approach should be further inspected.