- Email: [email protected]
Seven-year follow-up of combined cataract extraction and viscocanalostomy
J CATARACT REFRACT SURG - VOL 32, DECEMBER 2006
Seven-year follow-up of combined cataract extraction and viscocanalostomy Manijeh S. Wishart, MD, FRCS, FRCOphth, Evgenios Dagres, MD
PURPOSE: To investigate the long-term success and complications of phacoemulsification combined with viscocanalostomy (phacoviscocanalostomy) in eyes with coexisting cataract and medically uncontrolled glaucoma. SETTING: Department of Ophthalmology, Warrington Hospital, Warrington, United Kingdom. METHODS: A prospective nonrandomized study evaluated 165 consecutive eyes (114 patients) that had phacoviscocanalostomy. The main outcome measures were intraocular pressure (IOP), visual acuity, requirement for topical antiglaucoma medication, and the presence or absence of drainage blebs or bleb complications. RESULTS: The mean follow-up was 38.7 months G 19.3 (SD) (range 12 to 90 months). There was a statistically significant decrease in IOP, from 24.1 G 5.1 mm Hg preoperatively to 13.8 G 8.1 mm Hg 1 day after surgery (P<.001), 16.0 G 4.1 mm Hg at 5 years (P<.001), and at all evaluations to the last follow-up. The mean number of medications per eye decreased significantly from 2.5 G 0.9 before surgery to 0.1 G 0.5 at last follow-up (P<.001). At the final follow-up, IOP was reduced by 33.2% (16.2 mm Hg versus 24.1 mm Hg). Complete success, defined as an IOP reduction of more than 30% from preoperative level without medications, was achieved in 48.5% of eyes, with 42% of eyes having an IOP of less than 16 mm Hg. The percentage fall in IOP was linearly related to the preoperative IOP level (P<.001). No eye developed a trabeculectomy-type bleb, and there were no bleb-related complications. CONCLUSIONS: Phacoviscocanalostomy was safe and effective for the management of eyes with coexisting cataract and medically uncontrolled glaucoma. It provided a stable and sustained reduction in IOP with a minimum requirement for topical medication. J Cataract Refract Surg 2006; 32:2043–2049 Q 2006 ASCRS and ESCRS
With an aging population in the developed world, there is an increasing prevalence of cataract and glaucoma. In eyes requiring cataract extraction and glaucoma surgery, combined surgery provides better long-term control of intraocular pressure (IOP) than cataract surgery alone,1 protection from postoperative IOP spikes after cataract surgery,1 and
Accepted for publication August 8, 2006. From the Department of Ophthalmology, Warrington Hospital, North Cheshire NHS Trust, Warrington, United Kingdom. Presented in part at the XXIIIrd Congress of the European Society of Cataract & Refractive Surgeons, Lisbon, Portugal, September 2005. Neither author has a financial or proprietary interest in any material or method mentioned. Corresponding author: Mrs. M. Wishart, Warrington Hospital Lovely Lane, Warrington WA5 1QG United Kingdom. E-mail: [email protected]. Q 2006 ASCRS and ESCRS Published by Elsevier Inc.
prevention of late failure of trabeculectomy that can occur when cataract surgery is performed in eyes with prior trabeculectomy.2–5 However, combined cataract extraction and trabeculectomy has been shown to be less effective at lowering IOP than trabeculectomy alone.6–9 Trabeculectomy fails when intraocular inflammatory mediators induce subconjunctival fibroblast proliferation and scarring of the drainage bleb. Black race10 and prolonged topical medications11 are among the most important risk factors for drainage bleb failure. Combining cataract extraction with trabeculectomy is regarded as a significant risk factor for failure of trabeculectomy for those of the black race.12 The use of mitomycin-C (MMC) is therefore recommended to improve the outcomes of phacotrabeculectomy13–16 However, the use of MMC is associated with a significant increase in the risk for the severe sight-threatening complications of trabeculectomy such as hypotony maculopathy, blebitis, bleb leaks, and endophthalmitis.17–20 0886-3350/06/$-see front matter doi:10.1016/j.jcrs.2006.08.035
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Viscocanalostomy lowers the IOP by internal drainage and does not produce blebs.21–23 Therefore, combined viscocanalostomy and phacoemulsification (phacoviscocanalostomy) may not be adversely affected by the release of inflammatory mediators that cause trabeculectomy bleb failure. Stegmann et al.21 showed viscocanalostomy is safe and effective in the management of glaucoma in black patients. Good short- to medium-term results of phacoviscocanalostomy in eyes with medically uncontrolled glaucoma have been reported.22–24 We present the results of a 7-year follow-up of all phacoviscocanalostomies performed in elderly white patients in a single center. This is an ongoing report of an earlier study.24 PATIENTS AND METHODS All consecutive patients requiring combined cataract and glaucoma surgery had phacoviscocanalostomy and were included in the study. Surgery was performed by a single surgeon (M.S.W.) at Warrington Hospital between July 1997 and October 2004. Full informed consent was obtained from each patient, and follow-up was carried out at the same center. Ethical approval for the study was obtained. Excluded from the study were eyes with synechial closure of the drainage angle, previous complicated ocular surgery, or uveitic glaucoma. Postoperative data recorded at each clinic visit included visual acuity, IOP measurement by Goldmann applanation tonometry, anterior chamber depth assessment, the presence and nature of filtering blebs, gonioscopy, and fundus examination. Tonometry was performed by unselected ophthalmic medical staff, reducing the risk for bias in IOP recording. These examinations, except gonioscopy, were performed at each postoperative visit, which were at 1 and 7 days, 1, 3, 6, and 9 months, and 1 year. Thereafter, examinations were at 6-month intervals.
Surgical Technique A 5.0 mm 5.0 mm superficial scleral flap was dissected. Within the borders of the first superficial flap, a second, deeper 4.0 mm 4.0 mm scleral block was cut to just above the level of the choroid. The dissection was continued forward to identify the scleral spur; anterior to this landmark, Schlemm’s canal was opened. At this point, cataract surgery was performed with entry into the anterior chamber via a corneal phaco tunnel under the forward corneal hinge of the superficial scleral flap. Standard phacoemulsification was performed, and a foldable acrylic IOL (AcrySof, Alcon) was implanted in the capsular bag. Schlemm’s canal was then deroofed and the dissection carried forward into the cornea to create a window of trabecular meshwork–Descemet’s membrane (TDW). Care was taken to ensure the inner endothelial lining of Schlemm’s canal and adjacent juxtacanalicular trabecular meshwork tissue was removed to allow aqueous outflow. Sodium hyaluronate 1% (Healon) was removed from the anterior chamber. The deep scleral block and adjacent roof of the canal was then excised. Sodium hyaluronate 1.4% (Healon GV) was injected into the cut ends of Schlemm’s canal and under the superficial flap. Interrupted 10-0 polyglactin (Vicryl) sutures were used to tightly close the superficial scleral flap (5 to 7 sutures) and conjunctival wound (2 sutures).
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Postoperatively, prednisolone acetate 1% (Pred Forte) was given every 4 hours for 1 week and then gradually tapered until stopped after 1 month. Fucidic acid 1% gel (Fucithalmic) was used twice a day for 1 week. No antimetabolites were used. The definition of complete surgical success was an IOP reduction of 30% or more from the preoperative level without medication. In addition, to allow comparison with other published studies of glaucoma surgery, complete surgical success was also defined as IOP 21 mm Hg or less with no additional topical medication and qualified success was IOP of 21 mm Hg or less with additional topical medication. Failure was defined as IOP greater than 21 mm Hg with or without medication or need for further filtering surgery. Kaplan-Meier life table analysis graphs were constructed to determine complete success rate for IOP of 21 mm Hg or less and 18 mm Hg mm Hg or less without medications. Also analyzed was whether eyes with preoperative narrow angles and previous laser iridotomies experienced a greater reduction in IOP than eyes with open angles and whether there was a difference in outcomes in eyes with preoperative IOP less than 21 mm Hg. Statistical Analysis Dichotomous variables were compared by the chi-square test; other variables were compared by the t test or the MannWhitney test as appropriate. Visual acuity was converted to decimal values before the paired t test was applied. Differences in postoperative pressure reduction between groups with different preoperative IOPs were compared by 1-way analysis of variance (ANOVA). A P value less than 0.05 was considered statistically significant. Analyses were performed with the SigmaStat software (version 2.0, Systat Software, Inc.). RESULTS
One hundred sixty-five eyes of 114 patients were enrolled in the study. The mean follow-up after surgery was 38.7 months G 19.3 (SD) (range 12 to 90 months). Follow-up was for a minimum of 12 months. Twenty-three patients (29 eyes) died during the follow-up period. Table 1 shows the demographic data for the study population. Complete surgical success (IOP reduction of 30% or more) was achieved in 48.5% of eyes at final follow-up. Forty-two percent of eyes had IOP of 15 mm Hg or less at the last follow-up. The alternative definition of complete surgical success (IOP 21 mm Hg or less on no medication) was achieved in 94% of eyes at 1 year, 91.6% at 2 years, 88.9% at 3 years, 83.6% at 4 years, and 80.6% at 5 years (Table 2). Figure 1 shows the IOP levels. There was a statistically significant decrease in IOP from 24.1 G 5.1 mm Hg preoperatively to 13.8 G 8.1 mm Hg 1 day after surgery (P!.001) and at all time points to the last follow-up (Figure 1). The mean IOP reduction was 7.9 mm Hg (33.2%) at the last follow-up. A postoperative IOP level of 21 mm Hg or less without medication was achieved in 141 eyes (85.4%), with 126 eyes (76%) achieving IOP of 18 mm Hg or less and 68 eyes (42%), of 15 mm Hg or less. Figure 2 shows the Kaplan-Meier probability of complete surgical success
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Table 1. Demographic data.
Demographic
Value
Eyes (n) 165 Patients (n) 114 Sex (male/female) 54/60 Mean age (y) G SD 77.0 G 8.4 Race All white Glaucoma type POAG 118 NA C laser iridotomy 24 PEX 21 Pigment dispersion 2 Eyes on glaucoma medication preop, n (%) 165 (100) Mean preop glaucoma medications per eye G SD 2.5 G 0.9 Mean duration of topical treatment (y) G SD 6.7 G 5.7 Mean IOP before surgery (mm Hg) G SD 24.0 G 5.0 Mean presenting IOP (mm Hg) 32.6 G 7.6 POAG Z primary open-angle glaucoma, NA Z narrow angle, PEXZ pseudoexfoliation glaucoma, IOP Z intraocular pressure
(IOP 21 mm Hg or less without medication). Figure 3 shows the Kaplan-Meier probability of IOP of 18 mm Hg or less. Twelve patients developed temporary IOP elevation of greater than 21 mm Hg in the first days after surgery as a result of retained ophthalmic viscosurgical device in the anterior chamber; IOP returned to normal values (21 mm Hg or less) within the first week. Therefore, for the Kaplan-Meier curve, IOP levels at 1 day and 1 week were excluded. Comparison of IOP reduction after phacoviscocanalostomy in 24 eyes that had narrow angles and previous neodymium:YAG laser (Nd:YAG) peripheral iridotomy with 141 eyes with open angles showed no statistically
significant difference between the 2 groups. The final IOP was 15.9 G 3.5 mm Hg in the peripheral iridotomy group and 16.1 G 3.0 mm Hg in the open-angle group (P Z.798). A pressure reduction of more than 30% was achieved in 65.4% in the peripheral iridotomy group and 46.7% in the open-angle group (P Z.126). Figure 4 shows the postoperative pressure reduction from preoperative values. The percentage drop in IOP achieved by phacoviscocanalostomy was linearly related to the preoperative IOP level (P!.001, ANOVA). Intraoperative pressure spikes of over 25 mm Hg were observed in 12 eyes (7.3%) 1 day after surgery and in 10 eyes (6.1%) 7 days after surgery. Table 2 shows the IOP and the number and percentage of eyes with surgical success and failure during the follow-up. At 1 year, 7 eyes (4.2%) were on topical medications; at 3 years, 7 eyes (7.8%); and at 4 years, 5 eyes (10.2%). The mean number of medications per eye decreased significantly by 96%, from 2.5 G 0.9 before surgery to 0.1 G 0.5 at the last follow-up (P!.001). Complications occurred in 22 eyes (13.3%). They were zonular dehiscence with no vitreous loss (2 eyes, 1.2%), posterior capsule tear with vitreous loss (1 eye, 0.6%), peripheral choroidal detachment not affecting the macula (4 eyes, 2.4%), and a tear of the TDW requiring peripheral iridotomy (7 eyes, 4.2%). In another 8 eyes (4.8%), a microperforation of the TDW was observed with no iris prolapse. Two eyes (1.2%) had loss of visual acuity resulting from progressive glaucomatous visual field loss, despite good IOP control (8 mm Hg and 15 mm Hg, respectively). Three eyes (1.8%) lost between 3 and 5 lines of acuity at 1 year, 2 years, and 2.8 years, respectively, as a result of progression of preexisting age-related macular degeneration.
Table 2. Outcomes.
Number (%) Time After Surgery 1d 1 wk 1 mo 6 mo 12 mo 24 mo 36 mo 48 mo 60 mo 72 mo Last FU
Number of Eyes
Mean IOP (mm Hg G SD)
Complete Success (IOP %21 mm Hg, No Medication)
Qualified Success (IOP %21 mm Hg on Medication)
Failure (IOP O21 mm Hg or Surgical Intervention)
165 165 165 165 165 131 90 49 31 17 165
13.8 G 8.1 15.8 G 6.4 15.3 G 3.8 15.4 G 3.4 15.9 G 3.7 16.4 G 2.9 17.3 G 3.1 17.1 G 3.7 16.0 G 4.1 16.6 G 4.4 16.2 G 3.5
145 (87.9) 140 (84.8) 153 (92.7) 157 (95.2) 155 (94.0) 120 (91.6) 80 (88.9) 41 (83.6) 25 (80.6) 15 (88.2) 141 (85.4)
0 0 2 (1.2) 3 (1.8) 6 (3.6) 4 (3.1) 4 (4.4) 4 (8.2) 2 (6.5) 0 12 (7.3)
20 (12.1) 25 (15.2) 10 (6.1) 5 (3.0) 4 (2.4) 7 (5.3) 6 (6.7) 4 (8.2) 4 (12.9) 2 (11.8) 12 (7.3)
FU Z follow-up; IOP Z intraocular presssure
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Figure 1. Serial measurements of IOP during follow-up. Vertical bars indicate mean G SD (Pre Z last measurement before surgery; day1 Z first day after surgery; w Z week after surgery; m Z months after surgery; y Z years after surgery).
Four eyes (2.4%) developed raised IOP and had unsuccessful Nd:YAG laser goniopuncture. These 4 eyes required further glaucoma surgery to achieve IOP control. One eye (0.6%) developed iris prolapse shortly after surgery. One eye (0.6%) developed transient cystoid macular edema 2 months after surgery, which resolved completely with topical steroid drops in 3 months. One eye (0.6%) developed a branch retinal vein occlusion not affecting the macula or the vision. No wound leak or shallow
Figure 3. Kaplan-Meier probability of IOP of 18 mm Hg or less with or without medication. Dots indicate censored cases (deceased or lost to follow-up).
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Figure 2. Kaplan-Meier probability of complete surgical success, defined as IOP of 21 mm Hg or less without medication. Dots indicate censored cases (deceased or lost to follow-up).
or flat anterior chamber was observed. No eye developed hypotony or hypotony maculopathy. One month after surgery, 84 eyes (51%) had no visible bleb and 81 eyes (49%) had localized tissue swelling over the site of the superficial scleral flap. These low blebs disappeared in all eyes with follow-up of more than 2 years. No eye developed a thin-walled or cystic drainage bleb at any point during the follow-up. No eye developed late blebrelated complications. No case of bleb leak, hypotony,
Figure 4. Relationship between preoperative IOP levels and percentage reduction in IOP achieved by phacoviscocanalostomy (n Z number of eyes in each group).
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blebitis, or endophthalmitis occurred at any time during the follow-up. DISCUSSION
Our phacoviscocanalostomy results in 165 eyes of white patients with up to 7 years of follow-up indicate this technique was successful in controlling IOP and was not associated with the bleb-related complications seen with phacotrabeculectomy. Our patients had some significant risk factors for failure of trabeculectomy, namely combined surgery, prolonged topical medication, and high preoperative IOP.2,10–12 Therefore, had these eyes had phacotrabeculectomy, the use of MMC would have been recommended,16 exposing the patients to the risk for long-term bleb-related complications. Our 80.6% complete success rate (IOP 21 mm Hg or less) 5 years after surgery was better than that of unenhanced phacotrabeculectomy, which in a similar population had only a 55% complete success rate with 36 months of follow-up.25 Although long-term studies of phacotrabeculectomy with MMC report a mean pressure drop of 34% (to a mean IOP of 15 mm Hg) with MMC2,26 and a pressure drop of 25% to 16 mm Hg with 5-fluorouracil,27 these pressure levels were only achieved with the addition of a mean 1.0 medication per eye. We achieved a mean 33.2% pressure drop to a mean IOP of 16 mm Hg with virtually no medications (0.1 G 0.5). Carlson et al.15 report a mean IOP of 12.6 mm Hg after phacotrabeculectomy plus MMC on no medications; however, 15% of eyes had an IOP less than 5 mm Hg and 7.6% had endophthalmitis at 12 months. The risks of phacotrabeculectomy plus MMC are well described, with a 7% incidence of endophthalmitis28 and 3.7% hypotony reported by 2 years.14,28 Phacotrabeculectomy plus MMC has been reported to be responsible for up to 33% of cases of bleb-associated endophthalmitis.29 Although phacoviscocanalostomy is a relatively new procedure, there are other studies of phacoviscocanalostomy and phacoemulsification combined with deep sclerectomy with which to compare our results. Some authors report similar success rates to ours, achieving complete success rates of 90% to 95% between 12 months and 36 months postoperatively.30–32 Other studies report lower success rates. Differing success rates between different centers are a common experience with trabeculectomy studies, resulting in reported complete success rates at 1 year varying from 26% to 85%.33,34 Differing patient factors and differing surgeons may explain this wide range in outcomes, and it would therefore be unusual if there were not differences in success rates for phacoviscocanalostomy at different centers. Three examples of factors that could affect the outcome of phacoviscocanalostomy procedures are
differences in preoperative IOP levels, previous argon laser trabeculoplasty (ALT), and differing levels of surgical experience with the technique. In a recent study of phacoviscocanalostomy, Park et al.23 had 71% and 62% complete success rates at 12 months and 24 months, respectively. These patients had a significantly lower preoperative IOP (19 mm Hg) and a lower preoperative requirement for medication (1.0 per eye) than our study population. The percentage IOP drop in our study was linearly related to the preoperative IOP level (Figure 4), and Park et al.’s patients, with much lower preoperative IOP, might be expected to show a lower percentage fall in IOP. Another factor in comparing success rates in studies of nonpenetrating glaucoma surgery is whether the eyes had ALT, which has been described as being detrimental to the success of nonpenetrating techniques.35 Selective laser trabeculoplasty has been shown not to cause the scarring and destruction of Schlemm’s canal that can occur with ALT.36 Although Park et al.’s study excluded eyes with previous ALT, most studies only exclude eyes with ALT performed in the preceding 6 months. None of our eyes had previous ALT. Two studies37,38 of phacoemulsification combined with deep sclerectomy with small sample sizes (15 eyes in each) have reported complete success rates at 1 year of 73% and 46%, respectively. Such small numbers may indicate relative inexperience with a technique whose success is highly dependent on a technically accurate dissection to create a trabeculo-Descemet’s window. The results of phacoviscocanalostomy in our study appear to be better than those reported for viscocanalostomy alone.12,21,22 This is different from combined phacoemulsification and trabeculectomy, which has a worse outcome than trabeculectomy alone.6–9 Although our study only reports the results of phacoviscocanalostomy, we have reported better complete success rates in patients having phacoviscocanalostomy than viscocanalostomy alone.24 This has been the experience of other authors, with one study reporting 90% success with phacoemulsification– deep sclerotomy versus 62% for deep sclerotomy alone.30 Another reported a success rate for phacoemulsification– deep sclerotomy of 94% and 77% for deep sclerotomy after a 36-month follow-up.32 An indicator of improved success of phacoviscocanalostomy versus viscocanalostomy alone is less need for postoperative Nd:YAG laser goniopuncture, with most studies showing no need for Nd:YAG goniopuncture with phacoviscocanalostomy.30–32 Shaarawy et al.39 report a 50% rate of Nd:YAG goniopuncture with deep sclerectomy, and Gianoli et al.40 report a rate of only 21% with phacoemulsification–deep sclerotomy. There are 2 possible explanations that might help explain why combined nonpenetrating glaucoma surgery works better than combined trabeculectomy. The first is related to postoperative inflammation and its effect on
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aqueous drainage. Trabeculectomy works by outflow of aqueous through the sclerostomy into the subconjunctival filtering bleb. With no further trabecular meshwork function, Schlemm’s canal becomes smaller and scarred.41 This drainage is threatened by subconjunctival scarring that occurs when inflammatory mediators are released in response to intraocular surgery.42 As trabeculectomy produces more intraocular inflammation than nonpenetrating glaucoma surgery37,40 and phacoemulsification cataract extraction produces additional intraocular inflammation,43 the drainage bleb of combined phacotrabeculectomy is prone to scarring and failure. Viscocanalostomy does not rely on a drainage bleb but produces internal drainage, possibly into the cut ends of Schlemm’s canal; this drainage does not seem to be jeopardized by the release of inflammatory mediators from the eye. The second explanation is deepening of the anterior chamber. Removal of a cataract from the eye increases anterior chamber depth, reducing crowding of the anterior segment.44 Although this will not influence the outflow mechanism through the sclerostomy in phacotrabeculectomy eyes, with phacoviscocanalostomy, removal of the lens could allow better access of aqueous to the TDW and through the trabecular meshwork to Schlemm’s canal. Almost 15% of our eyes had narrow angles preoperatively and as a prophylaxis against angleclosure glaucoma had Nd:YAG laser peripheral iridotomy. Compared to the rest of the group, these eyes had a similar degree of IOP lowering, showing there was no relative degree of pupil block contributing to the raised IOP in these eyes. We excluded eyes with synechial closure of the anterior chamber angle as phacoemulsification alone has been shown as equally beneficial as filtration surgery in the treatment of acute angle-closure glaucoma.45 In our group, no eye developed a shallow or flat anterior chamber after surgery. A previous study38 found a 20% incidence of shallow anterior chamber and 6.7% incidence of flat anterior chamber after phacotrabeculectomy. No eye developed a permanent, visible drainage bleb, although in the early postoperative phase, 49% had a visible localized elevation of the conjunctival–episcleral tissue overlying the superficial scleral flap at the site of surgery. By the 7-year follow-up in our study, no patient had developed a bleb-related complication. There was a zero incidence of blebitis, endophthalmitis, bleb leak, hypotony, and hypotony maculopathy. We believe that the lack of a filtering bleb in our phacoviscocanalostomy patients represents a major advantage of this procedure over phacotrabeculectomy in terms of safety and quality of life as bleb dysesthesia is reported by 67% of patients after MMC trabeculectomy.46 The current trend in glaucoma surgery is to achieve the lowest pressure possible on the basis of the recent strong evidence that there is an association between lower IOP and
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reduced progression of visual field loss.47,48 The Advanced Glaucoma Intervention Study48 found that patients who consistently achieved an IOP below 18 mm Hg at all visits over 6 years had mean changes from baseline in their visual field defect score close to zero during follow-up. After phacoviscocanalostomy, the IOP was less than 18 mm Hg in 76% of our patients; therefore, the majority of our patients had IOP levels in this zone. In conclusion, phacoviscocanalostomy appeared to be uniquely safe in that no serious complications such as endophthalmitis, bleb leak, or hypotony occurred during the 7-year follow-up. Reduction in IOP was as good as that achieved with phacotrabeculectomy plus MMC and required less postoperative medications. There is, therefore, a strong case for recommending phacoviscocanalostomy in eyes with medically uncontrolled glaucoma and coexisting cataract.
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uncontrolled by medical therapy. Br J Ophthalmol 2004; 88:1012– 1017 Jampel HD, Friedman DS, Lubomski L, et al. Effect of technique on intraocular pressure after combined cataract and glaucoma surgery; an evidence-based review. Ophthalmology 2002; 109:2215–2224 Shin DH, Hughes BA, Song MS, et al. Primary glaucoma triple procedure with and without adjunctive mitomycin; prognostic factors for filtration failure. Ophthalmology 1996; 103:1925–1933 Carlson DW, Alward WLM, Barad JP, et al. A randomized study of mitomycin augmentation in combined phacoemulsification and trabeculectomy. Ophthalmology 1997; 104:719–724 Cioffi GA, Friedman DS, Pfeiffer N. Combined cataract/trabeculectomy. In: Weinreb RN, Crowston JG, eds, Glaucoma Surgery; Open Angle Glaucoma. The Hague, Kugler Publications, 2005; 65–72 Bindlish R, Condon GP, Schlosser JD, et al. Efficacy and safety of mitomycin-C in primary trabeculectomy; five-year follow-up. Ophthalmology 2002; 109:1336–1341; discussion by GL Spaeth, C Terzidou, A Bhan, 1341–1342 Song A, Scott IU, Flynn HW Jr, Budenz DL. Delayed-onset bleb-associated endophthalmitis; clinical features and visual acuity outcomes. Ophthalmology 2002; 109:985–991 Soltau JB, Rothman RF, Budenz DL, et al. Risk factors for glaucoma filtering bleb infections. Arch Ophthalmol 2000; 118:338–342 DeBry PW, Perkins TW, Heatley G, et al. Incidence of late-onset blebrelated complications following trabeculectomy with mitomycin. Arch Ophthalmol 2002; 120:297–300 Stegmann R, Pienaar A, Miller D. Viscocanalostomy for open-angle glaucoma in black African patients. J Cataract Refract Surg 1999; 25:316–322 Sunaric-Me´gevand G, Leuenberger PM. Results of viscocanalostomy for primary open-angle glaucoma. Am J Ophthalmol 2001; 132:221– 228 Park M, Tanito M, Takahashi H, Chihara E. Does the adjunctive peeling of juxtacanalicular tissue affect the outcome of two-site phaco-viscocanalostomy? J Glaucoma 2005; 14:224–229 Wishart MS, Shergill T, Porooshani H. Viscocanalostomy and phacoviscocanalostomy: long-term results. J Cataract Refract Surg 2002; 28:745–751 Kosmin AS, Wishart PK, Ridges PJG. Long-term intraocular pressure control after cataract extraction with trabeculectomy: phacoemulsification versus extracapsular technique. J Cataract Refract Surg 1998; 24:249–255 Shin DH, Iskander NG, Ahee JA, et al. Long-term filtration and visual field outcomes after primary glaucoma triple procedure with and without mitomycin-C. Ophthalmology 2002; 109:1607–1611 Ren J, Shin DH, O’Grady JM, et al. Long-term outcome of primary glaucoma triple procedure with adjunctive 5-fluorouracil. Graefes Arch Clin Exp Ophthalmol 1998; 236:501–506 Belyea DA, Dan JA, Lieberman MF, Stamper RL. Midterm follow-up results of combined phacoemulsification, lens implantation, and mitomycin-C trabeculectomy procedure. J Glaucoma 1997; 6:90–98 Busbee BG, Recchia FM, Kaiser R, et al. Bleb-associated endophthalmitis; clinical characteristics and visual outcomes. Ophthalmology 2004; 111:1495–1503; discussion by RK Parrish, 1503 D’Eliseo D, Pastena B, Longanesi L, et al. Comparison of deep sclerectomy with implant and combined glaucoma surgery. Ophthalmologica 2003; 217:208–211
31. Tanito M, Park M, Nishikawa M, et al. Comparison of surgical outcomes of combined viscocanalostomy and cataract surgery with combined trabeculotomy and cataract surgery. Am J Ophthalmol 2002; 134: 513–520 32. Wishart PK, Wishart MS, Porooshani H. Viscocanalostomy and deep sclerectomy for the surgical treatment of glaucoma: a long-term follow-up. Acta Ophthalmol Scand 2003; 81:343–348 33. Chaudhry IA, Pasha MA, O’Connor DJ, et al. Randomized controlled study of low-dose 5- fluorouracil in primary trabeculectomy. Am J Ophthalmol 2000; 130:700–703 34. Edmunds B, Thompson JR, Salmon JF, et al. The National Survey of Trabeculectomy. II. Variations in operative technique and outcome. Eye 2002; 15:441–448 35. Dietlein TS, Jacobi PC, Lu¨ke C, Krieglstein GK. Morphological variability of the trabecular meshwork in glaucoma patients: implications for non-perforating glaucoma surgery. Br J Ophthalmol 2000; 84:1354– 1359 36. Kramer TR, Noecker RJ. Comparison of the morphological changes after selective laser trabeculoplasty and argon laser trabeculoplasty in human eye bank eyes. Ophthalmology 2001; 108:773–779 37. Di Staso S, Taverniti L, Genitti G, et al. Combined phacoemulsification and deep sclerectomy vs phacoemulsification and trabeculectomy. Acta Ophthalmol Scand Suppl 2000; 232:59–60 38. Cillino S, Di Pace F, Casuccio A, et al. Deep sclerectomy versus punch trabeculectomy with or without phacoemulsification; a randomized clinical trial. J Glaucoma 2004; 13:500–506 39. Shaarawy T, Mansouri K, Schnyder C, et al. Long-term results of deep sclerectomy with collagen implant. J Cataract Refract Surg 2004; 30:1225–1231 40. Gianoli F, Schnyder CC, Bovey E, Mermoud A. Combined surgery for cataract and glaucoma: phacoemulsification and deep sclerectomy compared with phacoemulsification and trabeculectomy. J Cataract Refract Surg 1999; 25:340–346 41. Johnson DH, Matsumoto Y. Schlemm’s canal becomes smaller after successful filtration surgery. Arch Ophthalmol 2000; 118:1251– 1256 42. Meyer-ter-Vehn T, Gebhardt S, Sebald W, et al. p38 inhibitors prevent TGF-b-induced myofibroblast transdifferentiation in human Tenon fibroblasts. Invest Ophthalmol Vis Sci 2006; 47:1500–1509 43. Siriwardena D, Kotecha A, Minassian D, et al. Anterior chamber flare after trabeculectomy and after phacoemulsification. Br J Ophthalmol 2000; 84:1056–1057 44. Hayashi K, Hayashi H, Nakao F, Hayashi F. Changes in anterior chamber angle width and depth after intraocular lens implantation in eyes with glaucoma. Ophthalmology 2000; 107:698–703 45. Jacobi PC, Dietlein TS, Lu¨ke C, et al. Primary phacoemulsification and intraocular lens implantation for acute angle-closure glaucoma. Ophthalmology 2002; 109:1597–1603 46. Budenz DL, Hoffman K, Zacchei A. Glaucoma filtering bleb dysesthesia. Am J Ophthalmol 2001; 131:626–630 47. Heijl A, Leske MC, Bengtsson B, et al. Reduction of intraocular pressure and glaucoma progression; results from the Early Manifest Glaucoma Trial. Arch Ophthalmol 2002; 120:1268–1279 48. The AGIS Investigators. The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration. Am J Ophthalmol 2000; 130:429–440
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Seven-year follow-up of combined cataract extraction and viscocanalostomy Manijeh S. Wishart, MD, FRCS, FRCOphth, Evgenios Dagres, MD
PURPOSE: To investigate the long-term success and complications of phacoemulsification combined with viscocanalostomy (phacoviscocanalostomy) in eyes with coexisting cataract and medically uncontrolled glaucoma. SETTING: Department of Ophthalmology, Warrington Hospital, Warrington, United Kingdom. METHODS: A prospective nonrandomized study evaluated 165 consecutive eyes (114 patients) that had phacoviscocanalostomy. The main outcome measures were intraocular pressure (IOP), visual acuity, requirement for topical antiglaucoma medication, and the presence or absence of drainage blebs or bleb complications. RESULTS: The mean follow-up was 38.7 months G 19.3 (SD) (range 12 to 90 months). There was a statistically significant decrease in IOP, from 24.1 G 5.1 mm Hg preoperatively to 13.8 G 8.1 mm Hg 1 day after surgery (P<.001), 16.0 G 4.1 mm Hg at 5 years (P<.001), and at all evaluations to the last follow-up. The mean number of medications per eye decreased significantly from 2.5 G 0.9 before surgery to 0.1 G 0.5 at last follow-up (P<.001). At the final follow-up, IOP was reduced by 33.2% (16.2 mm Hg versus 24.1 mm Hg). Complete success, defined as an IOP reduction of more than 30% from preoperative level without medications, was achieved in 48.5% of eyes, with 42% of eyes having an IOP of less than 16 mm Hg. The percentage fall in IOP was linearly related to the preoperative IOP level (P<.001). No eye developed a trabeculectomy-type bleb, and there were no bleb-related complications. CONCLUSIONS: Phacoviscocanalostomy was safe and effective for the management of eyes with coexisting cataract and medically uncontrolled glaucoma. It provided a stable and sustained reduction in IOP with a minimum requirement for topical medication. J Cataract Refract Surg 2006; 32:2043–2049 Q 2006 ASCRS and ESCRS
With an aging population in the developed world, there is an increasing prevalence of cataract and glaucoma. In eyes requiring cataract extraction and glaucoma surgery, combined surgery provides better long-term control of intraocular pressure (IOP) than cataract surgery alone,1 protection from postoperative IOP spikes after cataract surgery,1 and
Accepted for publication August 8, 2006. From the Department of Ophthalmology, Warrington Hospital, North Cheshire NHS Trust, Warrington, United Kingdom. Presented in part at the XXIIIrd Congress of the European Society of Cataract & Refractive Surgeons, Lisbon, Portugal, September 2005. Neither author has a financial or proprietary interest in any material or method mentioned. Corresponding author: Mrs. M. Wishart, Warrington Hospital Lovely Lane, Warrington WA5 1QG United Kingdom. E-mail: [email protected]. Q 2006 ASCRS and ESCRS Published by Elsevier Inc.
prevention of late failure of trabeculectomy that can occur when cataract surgery is performed in eyes with prior trabeculectomy.2–5 However, combined cataract extraction and trabeculectomy has been shown to be less effective at lowering IOP than trabeculectomy alone.6–9 Trabeculectomy fails when intraocular inflammatory mediators induce subconjunctival fibroblast proliferation and scarring of the drainage bleb. Black race10 and prolonged topical medications11 are among the most important risk factors for drainage bleb failure. Combining cataract extraction with trabeculectomy is regarded as a significant risk factor for failure of trabeculectomy for those of the black race.12 The use of mitomycin-C (MMC) is therefore recommended to improve the outcomes of phacotrabeculectomy13–16 However, the use of MMC is associated with a significant increase in the risk for the severe sight-threatening complications of trabeculectomy such as hypotony maculopathy, blebitis, bleb leaks, and endophthalmitis.17–20 0886-3350/06/$-see front matter doi:10.1016/j.jcrs.2006.08.035
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Viscocanalostomy lowers the IOP by internal drainage and does not produce blebs.21–23 Therefore, combined viscocanalostomy and phacoemulsification (phacoviscocanalostomy) may not be adversely affected by the release of inflammatory mediators that cause trabeculectomy bleb failure. Stegmann et al.21 showed viscocanalostomy is safe and effective in the management of glaucoma in black patients. Good short- to medium-term results of phacoviscocanalostomy in eyes with medically uncontrolled glaucoma have been reported.22–24 We present the results of a 7-year follow-up of all phacoviscocanalostomies performed in elderly white patients in a single center. This is an ongoing report of an earlier study.24 PATIENTS AND METHODS All consecutive patients requiring combined cataract and glaucoma surgery had phacoviscocanalostomy and were included in the study. Surgery was performed by a single surgeon (M.S.W.) at Warrington Hospital between July 1997 and October 2004. Full informed consent was obtained from each patient, and follow-up was carried out at the same center. Ethical approval for the study was obtained. Excluded from the study were eyes with synechial closure of the drainage angle, previous complicated ocular surgery, or uveitic glaucoma. Postoperative data recorded at each clinic visit included visual acuity, IOP measurement by Goldmann applanation tonometry, anterior chamber depth assessment, the presence and nature of filtering blebs, gonioscopy, and fundus examination. Tonometry was performed by unselected ophthalmic medical staff, reducing the risk for bias in IOP recording. These examinations, except gonioscopy, were performed at each postoperative visit, which were at 1 and 7 days, 1, 3, 6, and 9 months, and 1 year. Thereafter, examinations were at 6-month intervals.
Surgical Technique A 5.0 mm 5.0 mm superficial scleral flap was dissected. Within the borders of the first superficial flap, a second, deeper 4.0 mm 4.0 mm scleral block was cut to just above the level of the choroid. The dissection was continued forward to identify the scleral spur; anterior to this landmark, Schlemm’s canal was opened. At this point, cataract surgery was performed with entry into the anterior chamber via a corneal phaco tunnel under the forward corneal hinge of the superficial scleral flap. Standard phacoemulsification was performed, and a foldable acrylic IOL (AcrySof, Alcon) was implanted in the capsular bag. Schlemm’s canal was then deroofed and the dissection carried forward into the cornea to create a window of trabecular meshwork–Descemet’s membrane (TDW). Care was taken to ensure the inner endothelial lining of Schlemm’s canal and adjacent juxtacanalicular trabecular meshwork tissue was removed to allow aqueous outflow. Sodium hyaluronate 1% (Healon) was removed from the anterior chamber. The deep scleral block and adjacent roof of the canal was then excised. Sodium hyaluronate 1.4% (Healon GV) was injected into the cut ends of Schlemm’s canal and under the superficial flap. Interrupted 10-0 polyglactin (Vicryl) sutures were used to tightly close the superficial scleral flap (5 to 7 sutures) and conjunctival wound (2 sutures).
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Postoperatively, prednisolone acetate 1% (Pred Forte) was given every 4 hours for 1 week and then gradually tapered until stopped after 1 month. Fucidic acid 1% gel (Fucithalmic) was used twice a day for 1 week. No antimetabolites were used. The definition of complete surgical success was an IOP reduction of 30% or more from the preoperative level without medication. In addition, to allow comparison with other published studies of glaucoma surgery, complete surgical success was also defined as IOP 21 mm Hg or less with no additional topical medication and qualified success was IOP of 21 mm Hg or less with additional topical medication. Failure was defined as IOP greater than 21 mm Hg with or without medication or need for further filtering surgery. Kaplan-Meier life table analysis graphs were constructed to determine complete success rate for IOP of 21 mm Hg or less and 18 mm Hg mm Hg or less without medications. Also analyzed was whether eyes with preoperative narrow angles and previous laser iridotomies experienced a greater reduction in IOP than eyes with open angles and whether there was a difference in outcomes in eyes with preoperative IOP less than 21 mm Hg. Statistical Analysis Dichotomous variables were compared by the chi-square test; other variables were compared by the t test or the MannWhitney test as appropriate. Visual acuity was converted to decimal values before the paired t test was applied. Differences in postoperative pressure reduction between groups with different preoperative IOPs were compared by 1-way analysis of variance (ANOVA). A P value less than 0.05 was considered statistically significant. Analyses were performed with the SigmaStat software (version 2.0, Systat Software, Inc.). RESULTS
One hundred sixty-five eyes of 114 patients were enrolled in the study. The mean follow-up after surgery was 38.7 months G 19.3 (SD) (range 12 to 90 months). Follow-up was for a minimum of 12 months. Twenty-three patients (29 eyes) died during the follow-up period. Table 1 shows the demographic data for the study population. Complete surgical success (IOP reduction of 30% or more) was achieved in 48.5% of eyes at final follow-up. Forty-two percent of eyes had IOP of 15 mm Hg or less at the last follow-up. The alternative definition of complete surgical success (IOP 21 mm Hg or less on no medication) was achieved in 94% of eyes at 1 year, 91.6% at 2 years, 88.9% at 3 years, 83.6% at 4 years, and 80.6% at 5 years (Table 2). Figure 1 shows the IOP levels. There was a statistically significant decrease in IOP from 24.1 G 5.1 mm Hg preoperatively to 13.8 G 8.1 mm Hg 1 day after surgery (P!.001) and at all time points to the last follow-up (Figure 1). The mean IOP reduction was 7.9 mm Hg (33.2%) at the last follow-up. A postoperative IOP level of 21 mm Hg or less without medication was achieved in 141 eyes (85.4%), with 126 eyes (76%) achieving IOP of 18 mm Hg or less and 68 eyes (42%), of 15 mm Hg or less. Figure 2 shows the Kaplan-Meier probability of complete surgical success
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Table 1. Demographic data.
Demographic
Value
Eyes (n) 165 Patients (n) 114 Sex (male/female) 54/60 Mean age (y) G SD 77.0 G 8.4 Race All white Glaucoma type POAG 118 NA C laser iridotomy 24 PEX 21 Pigment dispersion 2 Eyes on glaucoma medication preop, n (%) 165 (100) Mean preop glaucoma medications per eye G SD 2.5 G 0.9 Mean duration of topical treatment (y) G SD 6.7 G 5.7 Mean IOP before surgery (mm Hg) G SD 24.0 G 5.0 Mean presenting IOP (mm Hg) 32.6 G 7.6 POAG Z primary open-angle glaucoma, NA Z narrow angle, PEXZ pseudoexfoliation glaucoma, IOP Z intraocular pressure
(IOP 21 mm Hg or less without medication). Figure 3 shows the Kaplan-Meier probability of IOP of 18 mm Hg or less. Twelve patients developed temporary IOP elevation of greater than 21 mm Hg in the first days after surgery as a result of retained ophthalmic viscosurgical device in the anterior chamber; IOP returned to normal values (21 mm Hg or less) within the first week. Therefore, for the Kaplan-Meier curve, IOP levels at 1 day and 1 week were excluded. Comparison of IOP reduction after phacoviscocanalostomy in 24 eyes that had narrow angles and previous neodymium:YAG laser (Nd:YAG) peripheral iridotomy with 141 eyes with open angles showed no statistically
significant difference between the 2 groups. The final IOP was 15.9 G 3.5 mm Hg in the peripheral iridotomy group and 16.1 G 3.0 mm Hg in the open-angle group (P Z.798). A pressure reduction of more than 30% was achieved in 65.4% in the peripheral iridotomy group and 46.7% in the open-angle group (P Z.126). Figure 4 shows the postoperative pressure reduction from preoperative values. The percentage drop in IOP achieved by phacoviscocanalostomy was linearly related to the preoperative IOP level (P!.001, ANOVA). Intraoperative pressure spikes of over 25 mm Hg were observed in 12 eyes (7.3%) 1 day after surgery and in 10 eyes (6.1%) 7 days after surgery. Table 2 shows the IOP and the number and percentage of eyes with surgical success and failure during the follow-up. At 1 year, 7 eyes (4.2%) were on topical medications; at 3 years, 7 eyes (7.8%); and at 4 years, 5 eyes (10.2%). The mean number of medications per eye decreased significantly by 96%, from 2.5 G 0.9 before surgery to 0.1 G 0.5 at the last follow-up (P!.001). Complications occurred in 22 eyes (13.3%). They were zonular dehiscence with no vitreous loss (2 eyes, 1.2%), posterior capsule tear with vitreous loss (1 eye, 0.6%), peripheral choroidal detachment not affecting the macula (4 eyes, 2.4%), and a tear of the TDW requiring peripheral iridotomy (7 eyes, 4.2%). In another 8 eyes (4.8%), a microperforation of the TDW was observed with no iris prolapse. Two eyes (1.2%) had loss of visual acuity resulting from progressive glaucomatous visual field loss, despite good IOP control (8 mm Hg and 15 mm Hg, respectively). Three eyes (1.8%) lost between 3 and 5 lines of acuity at 1 year, 2 years, and 2.8 years, respectively, as a result of progression of preexisting age-related macular degeneration.
Table 2. Outcomes.
Number (%) Time After Surgery 1d 1 wk 1 mo 6 mo 12 mo 24 mo 36 mo 48 mo 60 mo 72 mo Last FU
Number of Eyes
Mean IOP (mm Hg G SD)
Complete Success (IOP %21 mm Hg, No Medication)
Qualified Success (IOP %21 mm Hg on Medication)
Failure (IOP O21 mm Hg or Surgical Intervention)
165 165 165 165 165 131 90 49 31 17 165
13.8 G 8.1 15.8 G 6.4 15.3 G 3.8 15.4 G 3.4 15.9 G 3.7 16.4 G 2.9 17.3 G 3.1 17.1 G 3.7 16.0 G 4.1 16.6 G 4.4 16.2 G 3.5
145 (87.9) 140 (84.8) 153 (92.7) 157 (95.2) 155 (94.0) 120 (91.6) 80 (88.9) 41 (83.6) 25 (80.6) 15 (88.2) 141 (85.4)
0 0 2 (1.2) 3 (1.8) 6 (3.6) 4 (3.1) 4 (4.4) 4 (8.2) 2 (6.5) 0 12 (7.3)
20 (12.1) 25 (15.2) 10 (6.1) 5 (3.0) 4 (2.4) 7 (5.3) 6 (6.7) 4 (8.2) 4 (12.9) 2 (11.8) 12 (7.3)
FU Z follow-up; IOP Z intraocular presssure
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Figure 1. Serial measurements of IOP during follow-up. Vertical bars indicate mean G SD (Pre Z last measurement before surgery; day1 Z first day after surgery; w Z week after surgery; m Z months after surgery; y Z years after surgery).
Four eyes (2.4%) developed raised IOP and had unsuccessful Nd:YAG laser goniopuncture. These 4 eyes required further glaucoma surgery to achieve IOP control. One eye (0.6%) developed iris prolapse shortly after surgery. One eye (0.6%) developed transient cystoid macular edema 2 months after surgery, which resolved completely with topical steroid drops in 3 months. One eye (0.6%) developed a branch retinal vein occlusion not affecting the macula or the vision. No wound leak or shallow
Figure 3. Kaplan-Meier probability of IOP of 18 mm Hg or less with or without medication. Dots indicate censored cases (deceased or lost to follow-up).
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Figure 2. Kaplan-Meier probability of complete surgical success, defined as IOP of 21 mm Hg or less without medication. Dots indicate censored cases (deceased or lost to follow-up).
or flat anterior chamber was observed. No eye developed hypotony or hypotony maculopathy. One month after surgery, 84 eyes (51%) had no visible bleb and 81 eyes (49%) had localized tissue swelling over the site of the superficial scleral flap. These low blebs disappeared in all eyes with follow-up of more than 2 years. No eye developed a thin-walled or cystic drainage bleb at any point during the follow-up. No eye developed late blebrelated complications. No case of bleb leak, hypotony,
Figure 4. Relationship between preoperative IOP levels and percentage reduction in IOP achieved by phacoviscocanalostomy (n Z number of eyes in each group).
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blebitis, or endophthalmitis occurred at any time during the follow-up. DISCUSSION
Our phacoviscocanalostomy results in 165 eyes of white patients with up to 7 years of follow-up indicate this technique was successful in controlling IOP and was not associated with the bleb-related complications seen with phacotrabeculectomy. Our patients had some significant risk factors for failure of trabeculectomy, namely combined surgery, prolonged topical medication, and high preoperative IOP.2,10–12 Therefore, had these eyes had phacotrabeculectomy, the use of MMC would have been recommended,16 exposing the patients to the risk for long-term bleb-related complications. Our 80.6% complete success rate (IOP 21 mm Hg or less) 5 years after surgery was better than that of unenhanced phacotrabeculectomy, which in a similar population had only a 55% complete success rate with 36 months of follow-up.25 Although long-term studies of phacotrabeculectomy with MMC report a mean pressure drop of 34% (to a mean IOP of 15 mm Hg) with MMC2,26 and a pressure drop of 25% to 16 mm Hg with 5-fluorouracil,27 these pressure levels were only achieved with the addition of a mean 1.0 medication per eye. We achieved a mean 33.2% pressure drop to a mean IOP of 16 mm Hg with virtually no medications (0.1 G 0.5). Carlson et al.15 report a mean IOP of 12.6 mm Hg after phacotrabeculectomy plus MMC on no medications; however, 15% of eyes had an IOP less than 5 mm Hg and 7.6% had endophthalmitis at 12 months. The risks of phacotrabeculectomy plus MMC are well described, with a 7% incidence of endophthalmitis28 and 3.7% hypotony reported by 2 years.14,28 Phacotrabeculectomy plus MMC has been reported to be responsible for up to 33% of cases of bleb-associated endophthalmitis.29 Although phacoviscocanalostomy is a relatively new procedure, there are other studies of phacoviscocanalostomy and phacoemulsification combined with deep sclerectomy with which to compare our results. Some authors report similar success rates to ours, achieving complete success rates of 90% to 95% between 12 months and 36 months postoperatively.30–32 Other studies report lower success rates. Differing success rates between different centers are a common experience with trabeculectomy studies, resulting in reported complete success rates at 1 year varying from 26% to 85%.33,34 Differing patient factors and differing surgeons may explain this wide range in outcomes, and it would therefore be unusual if there were not differences in success rates for phacoviscocanalostomy at different centers. Three examples of factors that could affect the outcome of phacoviscocanalostomy procedures are
differences in preoperative IOP levels, previous argon laser trabeculoplasty (ALT), and differing levels of surgical experience with the technique. In a recent study of phacoviscocanalostomy, Park et al.23 had 71% and 62% complete success rates at 12 months and 24 months, respectively. These patients had a significantly lower preoperative IOP (19 mm Hg) and a lower preoperative requirement for medication (1.0 per eye) than our study population. The percentage IOP drop in our study was linearly related to the preoperative IOP level (Figure 4), and Park et al.’s patients, with much lower preoperative IOP, might be expected to show a lower percentage fall in IOP. Another factor in comparing success rates in studies of nonpenetrating glaucoma surgery is whether the eyes had ALT, which has been described as being detrimental to the success of nonpenetrating techniques.35 Selective laser trabeculoplasty has been shown not to cause the scarring and destruction of Schlemm’s canal that can occur with ALT.36 Although Park et al.’s study excluded eyes with previous ALT, most studies only exclude eyes with ALT performed in the preceding 6 months. None of our eyes had previous ALT. Two studies37,38 of phacoemulsification combined with deep sclerectomy with small sample sizes (15 eyes in each) have reported complete success rates at 1 year of 73% and 46%, respectively. Such small numbers may indicate relative inexperience with a technique whose success is highly dependent on a technically accurate dissection to create a trabeculo-Descemet’s window. The results of phacoviscocanalostomy in our study appear to be better than those reported for viscocanalostomy alone.12,21,22 This is different from combined phacoemulsification and trabeculectomy, which has a worse outcome than trabeculectomy alone.6–9 Although our study only reports the results of phacoviscocanalostomy, we have reported better complete success rates in patients having phacoviscocanalostomy than viscocanalostomy alone.24 This has been the experience of other authors, with one study reporting 90% success with phacoemulsification– deep sclerotomy versus 62% for deep sclerotomy alone.30 Another reported a success rate for phacoemulsification– deep sclerotomy of 94% and 77% for deep sclerotomy after a 36-month follow-up.32 An indicator of improved success of phacoviscocanalostomy versus viscocanalostomy alone is less need for postoperative Nd:YAG laser goniopuncture, with most studies showing no need for Nd:YAG goniopuncture with phacoviscocanalostomy.30–32 Shaarawy et al.39 report a 50% rate of Nd:YAG goniopuncture with deep sclerectomy, and Gianoli et al.40 report a rate of only 21% with phacoemulsification–deep sclerotomy. There are 2 possible explanations that might help explain why combined nonpenetrating glaucoma surgery works better than combined trabeculectomy. The first is related to postoperative inflammation and its effect on
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aqueous drainage. Trabeculectomy works by outflow of aqueous through the sclerostomy into the subconjunctival filtering bleb. With no further trabecular meshwork function, Schlemm’s canal becomes smaller and scarred.41 This drainage is threatened by subconjunctival scarring that occurs when inflammatory mediators are released in response to intraocular surgery.42 As trabeculectomy produces more intraocular inflammation than nonpenetrating glaucoma surgery37,40 and phacoemulsification cataract extraction produces additional intraocular inflammation,43 the drainage bleb of combined phacotrabeculectomy is prone to scarring and failure. Viscocanalostomy does not rely on a drainage bleb but produces internal drainage, possibly into the cut ends of Schlemm’s canal; this drainage does not seem to be jeopardized by the release of inflammatory mediators from the eye. The second explanation is deepening of the anterior chamber. Removal of a cataract from the eye increases anterior chamber depth, reducing crowding of the anterior segment.44 Although this will not influence the outflow mechanism through the sclerostomy in phacotrabeculectomy eyes, with phacoviscocanalostomy, removal of the lens could allow better access of aqueous to the TDW and through the trabecular meshwork to Schlemm’s canal. Almost 15% of our eyes had narrow angles preoperatively and as a prophylaxis against angleclosure glaucoma had Nd:YAG laser peripheral iridotomy. Compared to the rest of the group, these eyes had a similar degree of IOP lowering, showing there was no relative degree of pupil block contributing to the raised IOP in these eyes. We excluded eyes with synechial closure of the anterior chamber angle as phacoemulsification alone has been shown as equally beneficial as filtration surgery in the treatment of acute angle-closure glaucoma.45 In our group, no eye developed a shallow or flat anterior chamber after surgery. A previous study38 found a 20% incidence of shallow anterior chamber and 6.7% incidence of flat anterior chamber after phacotrabeculectomy. No eye developed a permanent, visible drainage bleb, although in the early postoperative phase, 49% had a visible localized elevation of the conjunctival–episcleral tissue overlying the superficial scleral flap at the site of surgery. By the 7-year follow-up in our study, no patient had developed a bleb-related complication. There was a zero incidence of blebitis, endophthalmitis, bleb leak, hypotony, and hypotony maculopathy. We believe that the lack of a filtering bleb in our phacoviscocanalostomy patients represents a major advantage of this procedure over phacotrabeculectomy in terms of safety and quality of life as bleb dysesthesia is reported by 67% of patients after MMC trabeculectomy.46 The current trend in glaucoma surgery is to achieve the lowest pressure possible on the basis of the recent strong evidence that there is an association between lower IOP and
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reduced progression of visual field loss.47,48 The Advanced Glaucoma Intervention Study48 found that patients who consistently achieved an IOP below 18 mm Hg at all visits over 6 years had mean changes from baseline in their visual field defect score close to zero during follow-up. After phacoviscocanalostomy, the IOP was less than 18 mm Hg in 76% of our patients; therefore, the majority of our patients had IOP levels in this zone. In conclusion, phacoviscocanalostomy appeared to be uniquely safe in that no serious complications such as endophthalmitis, bleb leak, or hypotony occurred during the 7-year follow-up. Reduction in IOP was as good as that achieved with phacotrabeculectomy plus MMC and required less postoperative medications. There is, therefore, a strong case for recommending phacoviscocanalostomy in eyes with medically uncontrolled glaucoma and coexisting cataract.
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