Intraocular lens power prediction in a Vietnamese population A study to establish a limited set of intraocular lens powers that could be used in a Vietnamese population

Abstract

AIM: To determine a range of dioptric powers for Intraocular Lenses (IOLs) that would cover at least 95% of the Vietnamese population attending hospital for cataract removal and IOL implantation. OBJECTIVE: To determine the ocular axial lengths and keratometric powers of people attending for cataract surgery at a hospital in Vietnam and hence predict the intraocular lens powers required for emmetropia for this population. HYPOTHESIS: 95% of the population attending a Vietnamese hospital for cataract and intraocular lens surgery would be within ± 4.5 dioptres of the mean predicted emmetropic intraocular lens power. STUDY DESIGN: A case series. STUDY FACTORS: Axial length, keratometric power, age, sex, preoperative refractive status, preoperative vision, ethnicity. OUTCOME: Intraocular lens power for emmetropia. RESULTS: 346 adults attending for cataract surgery at the Hue Central Hospital, Vietnam were examined. The mean axial length was found to be 22.96 mm ± 0.99 (range 20.37–27.25), median 23.01 mm. The mean corneal power was 44.24 dioptres ± 1.53 (range 39.50–49.00), median 44.5 dioptres. Using the SRK/T formula, with an "A" constant of 118.3, the mean predicted intraocular lens power required for emmetropia was 21.44 dioptres ± 2.77 (range 10.87–27.25), median 21.56 dioptres. The mean predicted IOL power for females was 21.94 dioptres ± 2.60 (range 13.84–29.68), median 22.13 dioptres. The mean predicted IOL power for males was 20.72 dioptres ± 2.84 (range 10.87–28.95), median 20.66 dioptres. conclusion 95% of the population attending for cataract surgery were within 5.5 dioptres of the mean predicted emmetropic IOL power.