Cataract in keratoconus: Six-month results and a comparison of standard intraocular lens power calculation formulas

PURPOSE: To report the results of cataract surgeries in keratoconus patients at 1 and 6 months postoperatively, and to compare the standard intraocular lens (IOL) calculation formulas in this population. METHODS: This is a retrospective study, carried out in 44 eyes of 26 patients known to have keratoconus who underwent cataract surgery at Beirut Eye and ENT Specialist Hospital between 2010 and 2021. The patients were divided into groups based on Dr Jarade updated algorithm. Visual acuities before and after cataract surgery, at 1 and 6 months were recorded, as well as spherical equivalent. The difference between the expected spherical equivalent with each formula was subtracted from the actual resultant refraction, and its absolute value deduced. The means of the values were calculated and the 4 standard formulas (SRK/T, SRK/II, Holladay, and Hoffer Q) were compared. RESULTS: Six eyes had similar topographic and manifest axes (category 1) and underwent toric IOL implantation. Corrected distance visual acuity (CDVA) at 1 and 6 months was 0.2 and 0.1 logMAR, respectively. 26 eyes had mismatching axes and had monofocal IOL placement. CDVA at 1 and 6 months was 0.3. Six eyes required intrastromal corneal ring placement before operating (category 3). CDVA was 0.3 and 0.2 at 1 and 6 months, respectively. Regarding category 4, requiring keratoplasty and cataract extraction, CDVA was 0.4 at both follow-ups. No statistically significant difference was found between the different formulas. CONCLUSION: Categorization of keratoconus patients gave favorable results after cataract surgery. No superior IOL formula was found.