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PHILADELPHIA - Attention to elements of surgical technique and postoperative management will limit the risk of glaucoma developing after penetrating keratoplasty (PK). Sujatha Mohan MD reported a retrospective analysis of 184 eyes which had undergone PK at the annual ASCRS Symposium on Cataract, IOL and Refractive Surgery. The results showed that glaucoma developed in 48 (26%) eyes. Eyes with a primary diagnosis of aphakic bullous keratopathy (ABK), pseudophakic bullous keratopathy (PBK) and vascularised scars were at equally high risk (29% to 33%). Re-grafting was also associated with a high rate of glaucoma development (55%). While follow-up for the group averaged only 12 months and ranged up to 36, visual outcome was poor (worse than 20/200) in 20 (42%) of the 48 eyes with glaucoma. "The rate of glaucoma post-PK is particularly high in developing countries like India where the most common indications for grafting are ABK, PBK and vascularised scars. "Our results are consistent with a report from Chandrasekar et al who observed that glaucoma developed in 27% of PK eyes at LV Prasad Eye Institute, Hyderabad, South India," Dr Mohan said. She added that, in contrast, a study from the Australian corneal graft registry found only a 7% incidence of glaucoma after PK, but that series had much fewer patients operated on for aphakic and pseudophakic bullous keratopathy. "Glaucoma after PK is a serious clinical problem not only because it occurs frequently but also because it can be difficult to diagnose. "Our experience illustrates that it is associated with a high risk of graft failure and vision loss due to glaucomatous optic atrophy. We therefore recommend attention to strategies that can help prevent this complication," she remarked. Her recommendations for prevention included liberal treatment with topical steroids to reduce ocular inflammation and the use of a disparate graft size (0.5 mm). A good anterior chamber reconstruction by means of iridoplasty should also be achieved to create a mechanically rigid diaphragm and mitigate progressive PAS formation. She said clinicians should be aware that anterior goniosynechiae may be present despite a deep-appearing anterior chamber. Aggressive lysis of those adhesions is indicated to prevent PAS formation. The PK eyes in her series were operated on between January 1999 and January 2002 and had a minimum follow-up time of three months. A diagnosis of glaucoma was made based on the presence of IOP chronically elevated to 20 mm Hg or above. Of the 184 eyes in the series, 74 (40%) had a primary diagnosis of ABK and 48 (26%) underwent grafting for PBK. A total of 21 (11%) eyes were operated on for a vascular adherent scar. The primary diagnoses in the remaining 41 eyes included keratoconus, dystrophies and leucomas. Glaucoma developed in only two (4.8%) of those. When patients were categorised by lens status, the rates of glaucoma in aphakes (34%) and pseudophakes (29%) were about two-fold higher compared to those in eyes where the natural lens was intact (14.5%). "We believe this pattern can probably be explained by damage inflicted to the angle structures during the prior surgery and that most of the pseudophakic patients underwent extracapsular cataract extraction with implantation of a sulcus-fixated lens which resulted in glaucoma," Dr Mohan explained. Not surprisingly, a history of multiple surgery was associated with a higher risk of glaucoma. The rate of glaucoma development was lowest among patients who had PK alone (12.5%). Eyes which had PK and IOL removal had the highest rate of glaucoma (31.2%) followed next by eyes which had PK and ECCE with an IOL in place (22.9%) and those undergoing PK with anterior vitrectomy (18.7%) or IOL exchange (14.5%). The risk of glaucoma also increased with an increasing number of graft procedures. The glaucoma rate was only 9.4% among 117 eyes that underwent a single PK, 25% among 36 eyes that had a re-graft and reached 90.3% in the subgroup of 31 eyes that underwent multiple re-grafts. Treatment for glaucoma was initiated in all eyes with beta-blocker monotherapy. At the last follow-up, only 29 eyes were still being managed medically and 21 of those were on two or more drugs. Nineteen eyes had undergone trabeculectomy with adjunctive mitomycin-C. Within the surgical group, eight eyes failed the initial filtering procedure and were subsequently treated with cryotherapy, cyclophotocoagulation or an Ahmed valve implant. Overall, nine of the 19 eyes that underwent surgery were considered treatment failures. Five other eyes had failed medical treatment but refused surgery. Visual outcomes were worse in eyes that went on to require surgery compared to those receiving medical management. Out of 28 eyes with visual acuity of 20/200 or better, 21 eyes (72%) out of 29 were from the medically managed group compared to only seven eyes (37%) out of 19 from the surgical group. The causes of poor vision in the remaining 20 eyes included graft rejection in four eyes, endothelial failure in five, glaucomatous optic atrophy in six and presence of posterior segment pathology in five. Glaucoma after keratoplasty - particularly in high-risk cases - is a serious and frequently occurring complication. Constant vigilance is required to prevent rapid visual loss. |
