The Distribution of Ocular Biometrics among Patients Undergoing Cataract Surgery
Background: Ocular biometry is essential in many clinical and research applications; for example, axial length is essential in intraocular lens
power calculation prior to cataract and refractive surgeries, making diagnosis of staphyloma, etc. Various factors affect their values. We intend
to study the distribution of ocular biometrics among cataract patients in our environment.
Materials and Methods: This is a cross-sectional observational study. One hundred fifty-one patients with bilateral cataract scheduled for cataract surgery during the 1-year study period (July 2016–June 2017) were consecutively recruited for the study. Medical records including age and gender were collected. Ocular biometric data including axial length (AL), anterior chamber depth (ACD), cataractous lens thickness (LT), and vitreous chamber depth (VCD) values were measured for both eyes before cataract operation for either eye, using an optical biometer (ophthalmic A/B ultrasound system: CAS-2000BER, England). All the metric data were observed by the same experienced ophthalmic technician to avoid interobserver error.
Result: The mean AL was 23.51 [95% confidence interval (CI), 23.33–23.64], mean ACD was 3.22mm (95% CI, 3.12–3.30), mean LT was 4.23mm (95% CI, 4.17–4.29), and the mean VCD was 16.06mm (95% CI, 15.89–16.20). AL was longer among those ages less than 30 years, ACD was decreasing with increasing age, and the mean LT was higher for ages 30 years and above. The median ACD was decreasing with increasing age
up to ≥50 years, whereas the median LT increased with increasing age. The male–female variation in mean AL and mean VCD were statistically significant (P < 0.001 by Mann–Whitney U test); however, the mean ACD and mean LT were not statistically significant (P = 0.110 and 0.496, respectively, by Mann–Whitney U test). The median AL was higher in males than females (24.00 vs 23.00), with an interquartile range (IQR) of 23.50 to 24.00mm in males, and for females was 22.50 to 24.00 mm. The median ACD was a little higher in males than females (3.30 vs 3.10 mm), with IQR was 2.90 to 3.50mm in males, and for females was 2.80 to 3.40 mm.
Conclusion: Age and sex should always be considered in making inferences from biometric data in ophthalmic practice.
Keywords: Anterior chamber depth, axial length, biometry, intraocular lens, lens thickness, vitreous chamber depth