Variations in Ocular Biometrics Related to Refractive Errors Among Adult Patients Attending the University Teaching Hospitals-Eye Hospital in Lusaka, Zambia

Abstract

Coordination among anatomical components (Ocular biometrics) of the eye [corneal and lens power (CP/LP), anterior chamber depth (ACD), lens thickness (LT), and axial length (AL)] determine the refractive state of the eye. Ocular biometric measurements are crucial for the selection of the correct IOL and prescription of power to achieve the desired refractive outcome after cataract surgery and refractive errors respectively. This was a cross-sectional study conducted at University Teaching Hospitals Eye Hospital in Lusaka– Zambia; from April to June 2021, to assess the relationship between ocular biometrics and refractive errors. The study involved the measurement of refractive errors and ocular biometrics (Axial length, Lens power, Lens thickness, anterior chamber depth, corneal dioptric power, corneal radius, and Pupil size) in 205 study participants aged between 16 and 60 years of which 64 (31.2%) were males and 141 (68.8%) were females. Refractive errors were measured with a KR-9600 auto keratore fractometer whilst Ocular biometric parameters were done using an Optilex 780 marvels 11 A/B Scan Dell ultrasonography machine and autokeratometry. Out of 205 recruited study participants, 135 (65.9%) had refractive errors. The proportion of types of refractive errors were 66 (48.9%), 39 (28.9%), 19 (14.1%), and 11 (8.1%) for myopia, presbyopia, astigmatism, and hyperopia respectively. Variations of ocular biometrics among participants showed that mean values of anterior chamber depth, axial length and pupil size were greater in myopic study participants (2.7 mm, 23. 9 mm, and 4.39 mm respectively). Mean Lens thickness was much thicker in Presbyopia (3.95+/-0.65) while Lens power varied across all types of REs. Ocular biometrics related to refractive errors were axial length, anterior chamber depth, and lens thickness. Axial length and anterior chamber depth associated strongly with Myopia while lens thickness was more linked to Presbyopia. Age (16 and 47) years, inheritance, and childhood-onset associated strongly with Myopia while Presbyopia increased with increase in age.