Relative anterior microphthalmos - Morphometric analysis and its implications fur cataract surgery

Purpose: To evaluate morphometric data and risk factors for complications o f cataract surgery in patients with relative anterior microphthalmos (RAM). Design: Retrospective, comparative study (Part I) and matched pairs analysi s with controls (Part II). Participants: Sixty-two patients with RAM who underwent cataract surgery at the Department of Ophthalmology, Ruprecht-Karls-University of Heidelberg, Germany, between 1989 and 1997. RAM is defined as eyes with horizontal corn eal diameters less than or equal to 11 mm, axial length of >20 mm, and no o ther morphologic malformation. Main Outcome Measures: Part I: Patients were examined preoperatively for an terior chamber (AC) depth, lens thickness, total axial length, and refracti on. Associated ocular pathologic conditions (such as glaucoma or previous s urgical interventions) were recorded. Part II: A matched pairs analysis con cerning the anatomic features was performed with a group of 17 patients wit h RAM and 17 patients (controls) that matched the RAM group in terms of axi al length, age, and gender but showed corneal diameters >11 mm. Results: Part I: Anatomic parameters in RAM showed an average corneal diame ter of 10.7 +/- 0.34 mm, AC depth of 2.20 +/- 0.49 mm, and average lens thi ckness of 5.05 +/- 0.45 mm. Fifty-five percent of the patients had myopic r efraction. There was a high incidence of glaucoma (77.4%), cornea guttata ( 45.2%), and pseudoexfoliation syndrome (16.1%) in the RAM group. Sixty perc ent of patients had undergone previous glaucoma surgery. After cataract sur gery, 51.2% of patients achieved a visual acuity of >20/40 and 69.8% of >20 /50. Temporary corneal edema (54.8%) and ciliolenticular block (11.6%) were the most important complications after cataract surgery. Part II: Matched pairs analysis showed significant differences between RAM and controls in t erms of AC depth (P = 0.029) but no difference in lens thickness (P = 0.12) . Conclusions: Relative anterior microphthalmos can be characterized in terms of morphometric data as eyes with corneal diameters less than or equal to 11 mm and AC depths of 2 mm. The small anterior segment, especially the sha llow anterior chamber, is responsible for the high incidence of glaucoma an d postoperative complications after cataract surgery. Identifying these pat ients before surgery helps the cataract surgeon to be prepared for potentia l problems. Ophthalmology 2000;107:1555-1560 (C) 2000 by the American Acade my of Ophthalmology.