Cataract Surgery Outcome In Patients With Nanophthalmos: Reporting Results From A Large Real-Life Study

Nanophthalmos refers to an eye with a short axial length (AL), defined as less than or equal to 20 mm. It is a rare condition, with an estimated prevalence of approximately 0.27% in the UK population. Nanophthalmic eyes pose significant challenges for cataract surgery, including increased risks of complications and refractive surprises. There is limited literature on surgical outcomes in this patient population. This case series aims to present the visual outcomes and complications associated with cataract surgery in patients with nanophthalmic eyes in Gloucestershire, UK.

Gloucestershire is a rural county in England with a population of nearly 650,000. All non-routine cataract surgeries are exclusively referred to the Gloucestershire Eye Unit (GEU) for assessment and treatment. Between 1 January, 2006, and 31 December, 2023, a total of 62,364 cataract operations were performed on 41,366 patients aged 17 and older at the GEU. During this 18-year period, 86 nanophthalmic eyes underwent cataract surgery. 

We conducted a retrospective review of all patients with nanophthalmos who underwent cataract surgery in Gloucestershire. Cases were identified using the electronic health record (EHR) system Medisoft®. Data was obtained from both EHR and paper records. Patients under the age of 17 and those with inaccurate biometry were excluded from the study. Collected data included demographic and clinical characteristics, biometry measurements, intraocular lens (IOL) details, surgical procedures, and intraoperative and postoperative complications. Data analysis was performed using R.

On average, post-op best-corrected visual acuity (BCVA) improved by −0.206 logMAR (95% confidence interval: −0.278 to −0.135). 12 cataract surgeries required additional intraoperative procedures. Six eyes were left aphakic. Significant intraoperative complications included zonular dialysis (n = 5), posterior capsule rupture (n = 2), aqueous misdirection (n = 1); and post operatively: macular oedema (n = 4), malignant glaucoma (n = 2), exudative retinal detachment (n = 2), corneal decompensation (n = 2). Each 1 mm change in AL was associated with a 15.8% change in the complication rate. In this cohort, the Hoffer Q IOL formula was more frequently linked to refractive surprises and post-op myopic shifts.

At GEU, for every 725 cataract surgeries, there was one case of nanophthalmos. Consistent with previous studies, our case series demonstrates that nanophthalmic eyes present surgical challenges. Eyes with very short axial lengths (<18 mm) exhibited less favourable outcomes, highlighting the need for a careful discussion of the associated risks during pre-op consultations. However, post-op outcomes are encouraging, with 85% of eyes achieving improved BCVA. Our findings also highlight the non-inferiority of the SRK/T IOL formula compared to the Hoffer Q for predicting IOL power. This case series contributes to the evidence base for cataract surgery, supporting surgeons and patients in making informed decisions about surgery and IOL selection.