CHANGES OF PERIPAPILLARY NERVE FIBER LAYER AND FOVEAL THICKNESS MEASUREMENTS BY OPTICAL COHERENCE TOMOGRAPHY AFTER PHACOEMULSIFICATION IN NON-DIABETIC NON-GLAUCOMATOUS PATIENTS WITH SENILE GRADE 1+ CATARACT

Field: Medicine (Health Sciences)

Background: Optical coherence tomography (OCT) is widely used by ophthalmologists for diagnosing and following retinal diseases such as diabetic retinopathy (DR), and OCT measurement of peripapillary nerve fiber layer (NFL) thickness is valuable for glaucoma screening and detection of progression. Previous studies reported that the presence of visually significant cataract can affect the quality and accuracy of NFL and foveal thickness measurements by OCT because cataract increases light scattering and absorption. The effect of age related low grade cataract on OCT measurements has not been widely investigated. Objective: Studying the changes of peripapillary NFL and foveal thickness measurements by OCT after phacoimulsification and intraocular lens (IOL) implantation in non diabetic non glaucomatous patients with grade 1+ senile cataract. Patients and methods: This prospective study included 20 eyes of 20 patients (12 females and 8 males) with grade 1+ senile cataract [according to world health organization (WHO) criteria for cataract grading] which permits OCT imaging with reliable signal strength (SS). Patients with chronic systemic diseases such as diabetes mellitus (DM) and uncontrolled hypertension were excluded. Patients with dense or posterior subcapsular (PSC) cataract, patients with high myopia and patients with signs or OCT findings of glaucoma or maculopathy were also excluded. Detailed personal history, medical history, and ophthalmic history were taken at base-line for all patients, and full ophthalmologic examination including refraction, best corrected visual acuity (BCVA), slit lamp examination of the anterior segment, applanation tonometry, and dilated fundus examination of the macula, disc, retinal blood vessels and retinal periphery by slit lamp biomicroscopy were done at base line examination. OCT images for peripapillary NFL and macula were taken for all participants preoperatively and after 5 weeks postoperatively at Al-Hussein University hospital using spectral OCT SLO combination imaging system (OPKO/OTI, USA). Results: The mean (M) age was 56.65±1.9 years. The M preoperative BCVA was 0.3±0.1. The M postoperative BCVA was 0.6±0.1. All preoperative and postoperative OCT images were reliable with SS ≥ 6. The M values of participants` minimum, average and maximum NFL measurements were increased significantly after phacoemulsification. The average NFL measurement increased significantly by 9.8 µm (11%) from 89.80±6.69 µm preoperatively to 99.6±3.82 µm postoperatively. By analyzing the NFL quadrants thickness scales, there was an increase in the peripapillary NFL M measurements in all quadrants postoperatively. This increase was statistically significant in the superior, nasal and inferior quadrants, while this increase was not statistically significant in the temporal quadrant. As regard macular OCT, the M foveal thickness increased significantly by 26.15 µm (15%) from 172.10 ± 50.05 µm preoperatively to 198.25 ± 27.95 µm postoperatively. Conclusion:Peripapillary NFL and foveal thickness parameters may increase significantly after uncomplicated phacoemulsification and posterior chamber bag foldable IOL implantation. The optical effect of media opacity caused by cataract should be taken into consideration during follow up of cases by OCT such as glaucomatous and diabetic patients. Detailed general and ophthalmologic history, full ophthalmologic examination and previous investigations should be taken into consideration when patients were followed up using OCT, and any changes just as incidence of early cataract should be written in the OCT report.