ECP has been used since the 1980s2 for the treatment of many types of glaucoma. Our study aimed to look at ECP outcomes specifically in patients of African descent with varied types and stages of glaucoma. Recently, a study by Francis et al14 has shown ECP combined with phacoemulsification to be effective at lowering IOP and decreasing IOP lowering medication dependence specifically in eyes with mild to moderate glaucoma that were previously controlled with IOP lowering medications. However, a recent study by Smith et al. indicated that those results are temporary9. Other studies have focused on ECP results without phacoemulsification in advanced and refractory glaucoma and found ECP to have similar efficacy when compared to AGV in patients with refractory glaucoma who have had a prior trabeculectomy5. Our results were consistent with the above findings5,14. Another prospective study by Gayton et al15 comparing ECP combined with phacoemulsification to phacoemulsification alone in patients with prior trabeculectomy found comparable IOP lowing results and decreased IOP lowering medication dependence. A retrospective review by Chen et al. also found ECP to be safe and effective in refractory glaucomas of various types, including in patients who have had previous trabeculectomy or tube shunts16. Recently, Murakami et al. noted ECP to function equivalently to a second glaucoma drainage device in eyes that have had a prior drainage device implanted17. ECP has even been studied in difficult pediatric glaucoma cases including congenital glaucoma, aphakia, Sturge-Weber syndrome, and aniridia7,18. Despite the limited but varied data regarding ECP, only one previous study has looked specifically at results of ECP in a population of patients of African descent. This study found post-operative inflammation to be higher in patients of African descent but did not find any differences in IOP or BCVA when compared to patients of Caucasian decent10. Studying the effects of combined ECP procedures in patients of African decent is important since refractory glaucoma is very common amongst these individuals despite maximal medical therapy and surgical interventions, thus rendering further options necessary10,19.
In our retrospective review, it appears that four patients received a robust IOP lowering of up to 40%. Specifically, a patient with severe stage CACG s/p trabeculectomy had a 42% reduction, another patient with severe stage POAG s/p AGV demonstrated a 42% reduction, a patient with severe stage POAG s/p selective laser trabeculoplasty (SLT) had a 38% reduction and a patient with moderate POAG with no prior intervention showed a 38% reduction. However, some patients did not respond to combined phacoemulsification and ECP. A review of the literature demonstrates both a similar degree of successful IOP lowering as well as failures resulting in IOP worsening and need for further surgery20. Thus, it is clear that not all patients will experience significant IOP lowering or even success from this procedure. When analyzing subsets of our population, 3 patients who had undergone either a prior trabeculectomy or AGV achieved significant IOP lowering. Combined ECP and phacoemulsification may be quite effective in these particular patients, which is consistent with results of prior studies5,16. Combined ECP and phacoemulsification was successful in 6 of 9 (67%) patients who have POAG. In seven of thirty eyes (22%) the IOP worsened following the procedure. Of these seven eyes, four of them were on fewer IOP lowering drops post-operatively than pre-operatively. Latanoprost or an equivalent prostaglandin analog was stopped after surgery. Perhaps discontinuing IOP lowering medications post-operatively caused the IOP to rise. Additionally, 2/7 (29%) patients who had a higher post-operative IOP developed CME. One patient with CME had POAG and another had chronic angle closure glaucoma. Of the patients who demonstrated worsening IOP post-operatively, there was a mix of glaucoma states and types and none had undergone prior filtering or tube shunt surgeries.
In our study, 4-6 clock hours, or 120-180 degrees of ciliary processes were treated through a single incision. While a previous study by Uram21 found this same amount of treatment to be efficacious, a few other studies seem to suggest that a greater treatment area is necessary to achieve adequate IOP lowering. One such study by Patel, et al. recommends treating at least 180 degrees while another by Zabrin, et al. found treating 240 degrees to be more effective2,22. More recently, Kahook compared 1-site of 240 degree ECP treatment versus 2-site ECP treatment of 240-360 degrees of ciliary processes in total and found that 2-site ECP combined with phacoemulsification resulted in a statistically significant lowering of IOP compared to 1-site ECP treatment. He also noted that 2-site ECP treatment resulted in less IOP medication dependence and that there was no difference in inflammation or complication rate in the 2-site group when compared to the 1-site group. Our lower complication rate in comparison to other studies may be related to the relatively smaller degree of ciliary processes treated; however, larger treatment areas may be more effective and may have a similar safety profile when compared to a smaller treatment area6. This may be a future area of comparison in patients of African descent.
The complication rate was low with a POD 1 IOP spike being the most common complication. This IOP spike resolved in all patients with the use of topical IOP lowering medications in the office. After adding Diamox 500mg by mouth post-operatively to all patients, no further POD 1 IOP spikes were noted. Only 1 patient required an AGV to further lower IOP; however, this patient had a pre-operative IOP of 48 mmHg and post-ECP/phacoemulsification the patient’s IOP dropped to 28 mmHg. Combined ECP/phacoemulsification was attempted in this patient prior to an AGV since the patient wanted to try a less invasive procedure prior to considering a drainage device. No patients developed severe complications such as hypotony, choroidal detachments, or fibrin in the anterior chamber. As mentioned above our lower complication rate in comparison to other studies could be related to the relatively smaller degree of ciliary processes treated. Only 1/32 (3%) developed a small hyphema which resolved without complication and 1/32 (3%) developed postoperative iritis which resolved with topical steroids. Both of these patients had POAG. In total, 2/32 (6%) developed CME. In a recent review from Kaplowitz, et al., complication rates were found to be higher than what was reported in our study: fibrin in the anterior chamber was noted in 22% of eyes, hyphema was noted in 11%, and CME was noted in 10%19. Our lower complication rate may be attributed to a smaller treatment area as noted previously.
Postoperatively, 2/32 (6%) achieved complete success with an IOP lowering of ≥20% off all IOP lowering medications. Despite the low percentage of complete success, no other studies have used this strict criterion for complete success in the setting of ECP. Both patients with complete success were of Haitian decent and had POAG. Qualified success, defined as IOP lowering of 20% from baseline at the last visit regardless of IOP lowering medication use, was found in 9/32 (28%). Similar criteria for qualified success have been used in other studies in the glaucoma literature23,24. In the qualified success group 5 were of Haitian decent. 7/9 had moderate to advanced POAG, 1 had advanced CACG and 1 had ocular hypertension. Thus, considering the complete and qualified success groups as a whole, POAG and Haitian descent seemed to be associated with significant IOP lowering post-operatively. When compared to the literature, our complete and qualified success rates are lower than that found in a recent study by Clement, et al. who used similar success criteria and found success in 55.5% of eyes at 12 months24. Perhaps this higher success rate was due to a larger area of treatment and shorter follow-up time. In our study, patients who were followed for greater than 12 months demonstrated a rise in IOP, perhaps suggesting that the pressure lowering effect of ECP is only temporary. However, due to the limited length of follow-up and with only 4/32 patients having reached the 12 month follow-up period, it would be difficult to make that conclusion without a larger sample size. ECP results have been variable, with some studies showing continued IOP lowering success for up to 2 - 3 years5,9,25. Perhaps our lower success rate over time could also be attributed to our population which has a higher proportion of advanced and refractory glaucoma, and to our smaller ECP treatment zone. Overall, IOP was decreased on average by 5% from baseline and on average all patients were able to be weaned off of 1 IOP lowering medication. Roberts et al. found that combined ECP and phacoemulsification resulted in lower IOPs early on, but IOP steadily increased throughout the 12-month follow-up period. This study stratified outcomes based on race but did not find any statistical difference amongst race. It noted that the only outcome associated with successful treatment was pre-operative IOP25. Our results are similar to a recent review of ECP combined with phacoemulsification by Rathi and Radcliffe26. Although as a whole we did not find a statistically significant drop in IOP status post treatment, we did find a statistically significant decreased dependence on IOP lowering medication following treatment.
In regards to postoperative visual acuity, the outcomes are excellent with an average BCVA of 20/26 (logMAR 0.114), including patients with limited visual potential due to advanced glaucoma or retinal pathology (i.e. epiretinal membrane). Furthermore 19/32 (59%) ended up with a BCVA of 20/20 (logMAR 0) and 28/32 (88%) achieved an BCVA of >20/30. Such visual acuity results compare to a study by Siegel et al27 which compared the results of ECP and phacoemulsification with phacoemulsification alone.
With regards to refractive outcomes, this study is only the third to look at such data. A recent retrospective review by Wang et al28 compared refractive results in combined ECP and phacoemulsification to phacoemulsification alone and found that in combined ECP cases, refractive outcomes were less predictable and these same patients often experienced a small myopic shift. Another retrospective review by Kang et al8 also found there to be more refractive variability postoperatively in eyes who underwent ECP combined with phacoemulsification compared to those who underwent phacoemulsification alone. We found 84% of patients to be within +1.00D which is similar to Kang et al.’s finding of 90% to be within this goal. Furthermore, only 48% of combined ECP cases were within ±0.50D of goal, while 100% of phacoemulsification without ECP cases were within ±0.50D of goal8. In our study, 5/32 (16%) were >±1.0D of goal. Of these 5 cases, 3 resulted in a myopic surprise and 2 resulted in a hyperopic surprise. 4/5 of these patients, 3 with POAG and 1 with CACG, who obtained a refractive surprise had advanced glaucoma, suggesting that perhaps patients with advanced disease are more likely to experience a refractive surprise. 18/32 (56%) ended up within ±0.50D of goal. These outcomes suggest that physicians should take extra care to adjust for intraocular lens power. Currently no formula exists to adjust for ECP combined phacoemulsification refractive outcomes. The quality of each pre-operative biometry, A-scan, and K’s were reviewed in our study and were found to be accurate. One explanation for the variable refractive surprises may be that the lens/zonule complex is attached to the ciliary body, which is non-uniformly ablated during ECP. Moreover, having only a small section of ciliary bodies ablated could result in shifts of the entire lens complex. Considering our study and the 2 prior studies, postoperative refractive surprises may be possible and patients need to be counseled accordingly.