CORNEAL EDEMA AFTER CATARACT SURGERY - CHANGES IN CORNEAL ENDOTHELIUM CELL CHARACTERISTICS

Abstract

Corneal edema is a common complication of cataract surgery, although tremendous improvements have been made in the surgical techniques, which decreased surgical eye trauma and complication rates. Normal endothelial cell density is 2000-3000 cells/mm2 in older individuals, which maintains the corneal clarity. Even ‘perfect’ cataract surgery does some damage to the endothelium. A significant postoperative endothelium density decrease can impair its ability to maintain corneal clarity, resulting in corneal edema, blurring of vision and ocular pain. Aggressive topical treatment in the first month after surgery may lead to recovery of the endothelial cells. Our aim was to establish the effects of cataract surgery on the characteristics of the corneal endothelium. We performed a prospective interventional clinical study of 30 patients, mean age 65±12 years, with senile cataract. Over 80% were hard cataracts: 18% hypermature, 66% grade 4 (brunescent) and 16% grade 3 cataracts. Uneventful phacoemulsification with IOL implantation was performed by one experienced phaco-surgeon in an outpatient setting. Preoperative parameters included: best-corrected visual acuity (BCVA) in Snellen decimal units, IOP, cataract density (slit lamp examination), corneal endothelium cell density (ECD) and hexagonality measured with a specular microscope. Intraoperative parameters included: phacoemulsification time and energy, irrigation–aspiration suction time. Standard phacoemulsification cataract surgery was performed with in-the-bag IOL implantation. Mean baseline parameters were: BCVA=0.1±0.13, IOP=15.7±2.7 mmHg, ECD=2,497±290 cells/mm2, cell hexagonality was 54.3±9.4%. Mean surgical parameters were: surgical time=9,3±2.9 minutes, phacoemulsification time=35.6±26.1 seconds, phacoemulsification energy=13.3±10.9J, irrigation–aspiration suction time=81.3±45.9 seconds. Acute postoperative corneal edema occurred in 4 eyes (13.3%). After one-week BCVA was 0.5±0.2. 9 eyes (30%) had visual acuity ≤0.5. They were treated aggressively with antibiotics (moxifloxacine), corticosteroid (dexamethasone) and hypertonic eye drops (sodium chloride (5%) and mannitol (20%)), every hour during the first week and gradually tapered in the 1 month. Antiglaucomatose eyedrops (timolol, brinzolamide) were used to control the IOP below 20 mmHg. After 1 month mean BCVA increased to 0.85±0.15 and all eyes reached BCVA higher than 0.6. IOP was stable at 15.4±2.0 mmHg. The mean endothelial cell loss was 19,1%. None of the eyes progressed to chronic edema. Corneal edema is a common complication after surgery of difficult cataracts. Even though the cataract density directly influences the postoperative condition of the corneal endothelium, surgical trauma is still considered the most common cause of corneal endothelial decompensation. Preoperative specular microscopy is very important to predict possible postoperative complications of the corneal endothelium and apply appropriate surgical techniques and materials. Modern phaco-techniques (low phaco-energy, small incision site, new irrigation solutions and OVDs) can significantly reduce endothelial cell loss after cataract surgery. It is recommended to treat postoperative corneal edema and inflammation with topical corticosteroids, topical hypertonic agents and to maintain intraocular pressure below 20 mmHg.