Late IOL subluxation and increased IOP share several etiologies, chief of which is pseudoexfoliation. Though IOL subluxation and lack of IOP control often co-exist[10, 11, 24, 25], they are commonly managed separately – first with addressing the IOL with repositioning or exchange, followed by IOP lowering as needed. This approach has some drawbacks, mainly loss of IOP control after the IOL surgery, even in eyes in which the IOP was previously well controlled[6, 25]. This may lead to progression of glaucomatous damage, which is particularly concerning in cases with advanced disease. If a subconjunctival filtration surgery is done as the first step in a staged approach, the functionality of the filtering bleb may be diminished when a second surgery is undertaken to fixate the IOL.
Significant advances in surgical approaches to repositioning and fixating subluxated IOLs as well as new surgical techniques for IOP control present an opportunity for combining the two in a single visit to the operating room. First, new techniques have popularized IOL fixation[21, 22, 26, 27], as a less invasive alternative to IOL exchange.
Second, new minimally invasive glaucoma surgeries (MIGS) have shown promise in IOP reduction using ab-interno approaches. GATT has been shown to be effective in primary and secondary open angle of glaucomas[8, 9, 31, 10–12, 14, 15, 28–30], and specifically in PXG.
Data about combined procedures addressing both glaucoma and IOL fixation is limited. Shin et al. published the results of transscleral suture-fixated PCIOL implantation in combination with trabeculectomy in patients with glaucoma. Mean IOP at final follow up was 16.7 mmHg, which is higher than the usually reported number for trabeculectomy with or without cataract extraction in studies with equivalent follow up, and 34% required one or more additional surgical procedures for IOP control. This suggests that the efficacy of the filtering procedure is likely diminished by this combination. It is well established that the efficacy of trabeculectomy is slightly diminished when combined with cataract extraction[23, 24]. It is likely that when combined with procedures involving exposure of the subconjunctival space such as scleral IOL-fixation this effect is more pronounced. In contrast to subconjunctival procedures, the effect of GATT does not seem to be diminished when combined with cataract surgery[17, 25, 26, 32].
Yuko Mano et. Al. published a case report showing good visual improvement with good unmedicated IOP control in a woman with a subluxated IOL and an uncontrolled IOP due to PXF who underwent a flanged scleral fixation of IOL combined with trabeculectomy. Pathak-Ray et. al. recently published a series of 8 eyes which underwent flanged scleral fixated IOL combined with different glaucoma procedures (trabeculectomy, needling of pre-existing bleb and Ahmed glaucoma valve implantation) with good results. One eye in this series needed additional intervention for IOL exchange (due to IOL breakage) and later an additional procedure for IOP control. None of the patients described in this series had PXF. Yusaku Miura et al. recently published results of 9 eyes which underwent flanged scleral fixated IOL combined with microhook trabeculotomy. Their series demonstrated good IOL position with good IOP Control in all patients.
Success was achieved in all patients in our study, and none needed further surgery for IOL position or IOP control. The 32% reduction in IOP and 80% reduction in medication use seen in our series compares favorably with current data on GATT, suggesting the addition of IOL fixation surgery doesn’t have a significant negative effect on the IOP lowering effect of this surgery. The good IOP lowering effect achieved with a conjunctival sparing approach is encouraging, because a subconjunctival filtering procedure can be performed in the future in these cases as needed as a standalone surgery with improved outcomes.
Two patients in our series lost some of their visual acuity. The first had a completely dark visual field at baseline (MD = -27.0 dB), and the other did not perform a visual field examination prior to surgery in our clinic, but had a very advanced damage with a totally cupped nerve. The vision loss is likely the result of the surgical exposure itself in eyes with very significant damage at baseline, rather than due to the specific nature of the surgery. This risk is doubled if a staged approach is chosen.
Limitations of this study include small sample size, retrospective nature, short follow up, and lack of IOL imaging and auxiliary glaucoma testing for some of the patients.
In conclusion, GATT and scleral of iris IOL fixation are well suited to be combined for the surgical treatment of increased IOP and IOL subluxation.