Relative anterior microphthalmus (RAM): Morphometrical analysis and its implications for cataract and glaucoma surgery
Hans E. Völcker, Gerd U. Auffarth
Department of Ophthalmology, Ruprecht-Karls-University of Heidelberg
Summary: Purpose: To evaluate morphometrical data and risk factors for cataract surgery in patients with relative anterior microphthalmus (RAM). RAM is defined as eyes with horizontal corneal diameters Ł 11mm, axial length of >20 mm without any malformation. Patients and Methods: Sixty two patients with RAM, who underwent cataract surgery, were examined for anterior chamber (AC) depth, lens thickness, total axial length (TAL) and refraction. Associated ocular pathology (such as glaucoma, previous surgical interventions, etc.) was recorded. In addition a matched pairs analysis concerning the anatomical features was performed with a group of 17 patients with RAM and 17 patients (controls) that matched the RAM group in terms of axial length, age and gender but showed corneal diameters >11 mm. Results: Anatomical parameters in RAM showed an average corneal diameter of 10.7?0.34 mm, AC-depth of 2.20?0.49 mm and average lens thickness of 5.05? 0.45 mm. Fifty five percent of patients revealed myopic refraction. There was a high incidence of glaucoma (77.4%), cornea guttata (45.2%) and Pseudoexfoliation syndrome (16.1%) in the RAM-group. Sixty percent of patients had undergone previous glaucoma surgery. Matched pairs analysis showed significant differences between RAM and controls in terms of AC-depth (p=0.029) but no difference in lens thickness (p=0.12). After cataract surgery 51.2% of patients achieved visual acuity of >20/40, 69.8% of >20/50. Temporary corneal edema (54.8%) and cilio-lenticular block (11.6%) were the most important complications after cataract surgery. Conclusions: Relative anterior microphthalmus can be characterized in terms of morphometrical data as eyes with corneal diameters Ł11 mm and anterior chamber depths of 2 mm. The small anterior segment, especially the shallow anterior chamber, is responsible for the high incidence of glaucoma and postoperative complications after cataract surgery. Identifying these patients prior to surgery helps the cataract surgeon to be prepared for potential problems.
Keywords: Ram, microphthalmus, anterior chamber depth, lens thickness, total axial lenght.