Analysis of visual outcome following cataract surgery in axial myopic patients

Abstract

Aim: The primary outcome is to assess visual outcomes following cataract surgery in axial myopic patients. The secondary outcome assessed is perioperative complications rate due to high axial length. Materials and Methods: Type of study: It was a retrospective, noncomparative case series study. Inclusion criteria: Patients with axial length more than or equal to 25 mm with visually significant cataract in one or both eyes were recruited for the study. Patients with pathological myopia were also included – visual recovery was assessed in conjunction with the preoperative best-corrected visual acuity. Exclusion criteria: Myopic patients with cataract with other causes of visual loss such as macular scar, diabetic retinopathy, age-related macular degeneration, disc edema, vein occlusion, and epiretinal membrane were excluded from the study. Sample Size: The sample size of the study was 32 patients (49 eyes). All patients recruited for the study underwent complete anterior segment examination in slit lamp with due importance to the type of cataract, visual acuity examination, and refraction to assess preoperative best-corrected visual acuity and posterior segment examination with 90 D lens. If the posterior segment was not visualized, B-scan was done. Blood investigations include complete blood count, random blood sugar, HIV, hepatitis B virus surface antigen, and urine albumin/sugar. With the test results and electrocardiogram, anesthetist fitness was obtained. Duct patency and intraocular pressure (IOP) were measured. Automated keratometry and axial length were measured by immersion technique done to calculate intraocular lens (IOL) power. IOL power calculation was performed using the SRK/T which was found to be reliable in axial lengths above 25 mm. Anterior chamber depth and lens thickness were also measured. All patients underwent phacoemulsification with IOL implantation by experienced single surgeon. The main outcomes measured were visual acuity after cataract surgery with implantation of zero or negative or very low IOL power at 1-month postoperative period and intraoperative and postoperative complications. The method of surgery did not influence the visual outcome. Results: The mean age of the patient operated on was about 61.9 years. In our study, the most common type of cataract was nuclear cataract (63.2%). Only 4.1% had previous refractive surgery. About 65.3% had 6/6 vision postcataract surgery with axial myopia. About 51.1% of axial myopic patients' fundus changes before cataract surgery which could be one of the causes for poor visual acuity. No significant perioperative complications were observed. Conclusion: Good postoperative outcomes following cataract surgery were observed in patients with cataract and high myopia. Refractive error is a potential complication as the hyperopic error appears to increase with axial length, especially in patients receiving negative power lens. If a sulcus IOL is inserted, it is more likely to be unstable or decenter because of the larger sulcus size. The need for Nd: YAG capsulotomy for posterior capsular opacity was found to be more common in myopes with high axial length compared to the general population. IOP reduction is slower and unstable for the first 30 days of postcataract surgery in highly myopic eyes.