Comparative Clinical Study of Medically Controlled Nonsevere Chronic Primary Angle-closure Glaucoma with Coexisting Cataract Surgically Managed by Phacoemulsification as against Combined Phacotrabeculectomy.

PURPOSE: Comparative clinical study of medically controlled non-severe chronic Primary Angle Closure Glaucoma (PACG) with co-existing cataract surgically managed by phacoemulsification as against combined phacotrabeculectomy.
METHODS: This randomized clinical trial was conducted between December 2011 and December 2013. Patients were randomly assigned to Phacoemulsification (PE) and Phacotrabeculectomy (PT) groups for surgery. Intraocular pressure, anti-glaucoma medications, Best Corrected Visual Acuity, anterior chamber angle widening and post-operative complications in both groups were compared after 12 months.
RESULTS: There were 46 eyes with PACG in PE group and 45 in PT group. The IOP at 12 months in PE group was 11.5±1.3mmHg and 11.8±1.2mmHg in PT gr. (p = 0.28). The eyes requiring single anti-glaucoma medications at 12months in PE group was 0, PT group was 1 (p = 0. 495). The post op BCVA at 12months in PE group 0.3+-0.12 and 0.33±0.15 in PT group (p = 0.22). 3 cases in PT group required additional intervention whereas no additional intervention was required in PE group and this difference was statistically significant (p = 0.116).
CONCLUSION: Phacoemulsification is equally effective in terms of intraocular pressure control and visual outcome as phacotrabeculectomy with better safety and less post-operative complication.

RCT Entities:   Population Interventions Outcomes

Introduction

Primary angle-closure glaucoma (PACG) is a common disease amongst Asians[1] and Indians.[2] Angle-closure glaucoma with a coexisting cataract may be treated with laser iridotomy, cataract extraction alone or combined cataract extraction, and trabeculectomy.[34567] However, combined cataract extraction and trabeculectomy may be fraught with potentially serious complications such as wound leak, over filtration, hypotony, choroidal detachment, and endophthalmitis.[89]

A thick anteriorly positioned lens plays an important role in causing angle-closure disease.[1011] In cases of chronic PACG, lens extraction causes anterior chamber deepening, widening of the angle, reducing the risk of further attacks, and significant intraocular pressure (IOP) lowering.[12131415] If IOP is not controlled, trabeculectomy can be done later without compromising long-term IOP control.[14] We proposed to compare the surgical outcomes of cataract extraction alone and cataract extraction combined with trabeculectomy in patients with PACG in our hospital.

Materials and Methods

Institutional Ethics Committee and Scientific Committee approval was obtained for conducting this randomized interventional case series which was carried out from December 2011 to December 2013. Our study adheres to the tenets of Declaration of Helsinki.

The sample size was calculated based on the assumption that the decrease in IOP (main outcome variable) pre- and postoperatively in both the group was 6 mmHg. The reference study considered was “Phacoemulsification versus combined phacotrabeculectomy (PT) in medically controlled chronic angle-closure glaucoma with cataract by Tham et al.[14] Software used – StatCalc-EpiCal calculator, confidence interval % – 95% (i.e., error alpha), power – 80 (i.e., error beta), assuming mean difference in IOP – 6 mmHg, standard deviation – 9.3 and 9.5, and the total sample size – 78. Considering the loss to follow-up of 15%, the total number of patients recruited was 91.

Patients with PACG and concomitant cataract, fulfilling the inclusion criteria, were randomized into Group A (phacoemulsification [PE] alone) and Group B (phacotrabeculectomy [PT]) using random number table software. Written informed consent was obtained. The two groups were compared with regard to IOP control, number of antiglaucoma medications required, and vision and surgical complications for a 12-month follow-up period.

Eyes with medically controlled PACG and coexisting cataract were included in the study. PACG was defined as 180° or more of angle closure, synechial or appositional. All patients had a patent yttrium-aluminum-garnet laser peripheral iridotomy. Medically controlled glaucoma[14] was taken as ≤21 mmHg with ≤3 topical drugs, glaucomatous optic disc changes, and visual field loss compatible with glaucoma.

Exclusion criteria were single functioning eye, previous intraocular surgery including surgical iridectomy, patients having severe angle-closure glaucoma. Mean deviation score >12 on visual field score using 30-2 Humphrey's visual field loss in one eye was considered as advanced glaucoma.[16]

General baseline information for each patient included age, gender, localization of eye undergoing surgery, and ocular medication. Preoperatively, all patients underwent a complete ophthalmic examination. Best-corrected visual acuity (BCVA) was assessed using Snellen's Chart and converted into LogMAR, IOP with Goldmann applanation tonometer, slit-lamp biomicroscopy of the anterior segment, indentation gonioscopy was done using Susmann four mirror lens and angle was graded according to Shaffer's system. Fundus examination was carried out using a Volk +90D or +78D lens. Automated white-on-white perimetry was done using 30-2, SITA-standard strategy (model 750, Humphrey Instruments, Dublin, CA). Number of IOP-lowering drugs were noted. The findings were documented for the study eye. Prostaglandin analogs were stopped 1 week before surgery and changed preoperatively to beta-blockers (timolol maleate 0.5%) with or without alpha-agonists. (Brimonidine – 0.2%). Intravenous mannitol 20% was given preoperatively over 60 min to achieve good IOP control.

Technique of phacotrabeculectomy

Under peribulbar block, a superior rectus traction suture using 4-0 black silk is placed. A fornix-based incision through the conjunctiva and Tenon's capsule is taken, dissected through Tenon's and the episclera to bare the sclera superiorly. Gentle cautery is applied at the surgical site. We have not used any antifibroblastic agent in these cases, as our earlier experience with trabeculectomy without mitomycin C had good long-term IOP control. A triangular superficial scleral flap of 4 by 4 by 4 mm at the superior limbus is dissected at approximately one-half scleral thickness into clear cornea. At this point, the traction suture is released, the anterior chamber is entered under the scleral flap. Phacoemulsification is performed through the opening under the scleral flap, with two corneal side port incisions. After completing intraocular lens implantation, the anterior chamber is filled with viscoelastic and trabeculectomy is done using Kelly's punch. Approximately 2 by 2 mm sclerotomy opening is made, followed by iridectomy. The trabeculectomy site is washed to clear any remnants of the sclera and iris pigments. The patency of the trabeculectomy is checked. The scleral flap is sutured with three 10/0 nylon sutures, one at the apex and two at the base. The apical suture is a little loose and the basal sutures are tight. The surgery site is checked for leakage. A slight leakage from the apex is desirable, with the anterior chamber remaining formed, and the eyeball not too hard. The conjunctiva-Tenon's layer is sutured with 8-0 Vicryl suture at the ends of the incision. The corneal side port incisions are hydrated and made watertight. A subconjunctival injection of gentamycin and dexamethasone 0.5 ml is given and the eyeball patched.

Technique of phacoemulsification

Under topical or peribulbar block, a corneal tunnel is made along the steep axis of the cornea. Two side port incisions are made and anterior chamber filled with a viscoelastic. A continuous curvilinear capsulorhexis is made, hydrodissection and delineation performed. A stop and chop or direct chop technique is used to perform the phacoemulsification. A foldable intraocular lens is implanted in the bag and viscoelastic aspirated.

The primary incision and side-port incisions are hydrated and sealed to achieve a watertight and stable anterior chamber. Care is taken not to hydrate more so as to have the eyeball not too hard. Subconjunctival gentamycin and dexamethasone injection are given in patients with peribulbar block, while patients with topical anesthesia are started on steroid and antibiotic eye drops within 6 h of surgery.

Postoperatively, all glaucoma eye drop was stopped. Postoperatively, in PE only, eyes with an IOP ≥21 mmHg were resumed on IOP-lowering drugs to maintain an IOP of ≤21 mmHg. Glaucoma drugs were added in the following order: Beta-blockers, adrenergic agonists, and carbonic anhydrase inhibitors. In PT group, if IOP >21, then it was assessed and if it was due to tight suture/scarring and then accordingly additional intervention was done [Table 1].

Table 1

Indications for additional surgery was as follows

Postoperative visits were scheduled at day 1 and 7; weeks 4, 8, and 12; and months 6 and 12. Parameters observed were IOP, number of antiglaucoma medications required (primary outcome measures). BCVA, angle status by indentation gonioscopy (after 8 weeks), complications (intraoperative and postoperative), and any additional interventions required to maintain filtration or to handle complications were secondary outcome measures. Progressions of glaucomatous optic nerve head morphology and visual field loss were not taken as surgical complications in this study.

Statistical methods

SPSS (Statistical Package for the Social Sciences) 18 was used for statistical analysis and P < 0.05 was considered statistically significant. Chi-square test was used for evaluating change in categorical variables. Continuous variable such as IOP and BCVA were analyzed using Student's t-test.

Results

The demographic and clinical profile of participant of PE and PT groups is compared in Table 2. All the preoperative variables were similar in two groups.

Table 2

Profile of participants with nonsevere angle-closure glaucoma undergoing phacoemulsification and phacotrabeculectomy surgery

The IOP at various time points of follow-up between the two groups is summarized in Figure 1. The mean preoperative IOP in the PE group was 26.72 ± 10.49 mmHg, and postoperatively, the IOP was 0.29 ± 0.12 mmHg. The mean preoperative IOP in the PT group was 26.43 ± 10.73 mmHg, and postoperatively, it was 11.81 ± 1.25 mmHg. There was no statistically significant difference (P ≥ 0.05) in mean IOP between the two treatment groups preoperatively and postoperatively at all follow-ups.

Figure 1

Comparison of mean postoperative intraocular pressure. This figure summarizes mean intraocular pressure of patients in the two groups at various follow-ups. By two independent samplet-test, the final mean intraocular pressure between the two groups at follow-up was not statistically significant (P> 0.05)

The requirement of antiglaucoma medicine in two groups is given in Table 3. There was significant difference in requirement of number of antiglaucoma PE and PT group at day 1, 1 week, 1 month (P = 0.242), 6 months, and 12 months (P = 0.495) postoperative follow-ups. However, the difference was insignificant in two groups before surgery (P = 0.819).

Table 3

Number of glaucoma medications at different follow-ups after phacoemulsification and phacotrabeculectomy surgeries for managing nonsevere chronic angle-closure glaucoma compared to glaucoma medications before surgery

The final vision between the two groups showed no statistically significant difference preoperatively and postoperatively at various follow-ups (P > 0.05) is summarized in Figure 2.

Figure 2

Final mean vision at various follow-ups. This figure summarizes mean vision (logMAR) in two groups at various follow-ups. By two independent samplet-test, mean vision (log MAR) between the two groups at final follow-up was not statistically significant

There was 1 case with wound leak in PT group which required resuturing and 2 patients with bleb scarring for which injection 5-Fluorouracil with bleb needling was done at 3-week postoperatively. Three cases in PT group required additional intervention whereas no additional intervention was required in the PE group and this difference was statistically significant in two groups (P = 0.116) [Table 4].

Table 4

Number of patients requiring additional intervention after phacoemulsification and phacotrabeculectomy surgeries

Angle widening in phacoemulsification and PT groups before surgery and at 12 months was noted. There was significant widening of angle postsurgery in both groups by Chi-square test. The angle widening at 12 months in both the groups were equal and statistically insignificant (P = 0.827) [Table 5].

Table 5

Comparison of angle between the two groups at 12-month follow-up

Discussion

Summary

The improvement in IOP and postoperative visual acuity were similar 12 months after phacoemulsification or PT surgeries. However, requirement of antiglaucoma medications, complication rates, need for additional intervention, and opening of angle of anterior chamber was significantly better after PE compared to PT in treatment of eyes with nonsevere chronic angle-closure glaucoma with cataract.

Intraocular pressure reduction in phacoemulsification and phacotrabeculectomy

Lens is known to cause narrowing of angle of anterior chamber in old age due to cataract development.[1011] Hayashi et al.[13] studied the effect of lens extraction on IOP had noted reduction of IOP and opening of angle of anterior chamber after removal of anteriorly placed lens. Removal of cataract and thereby making the angle of anterior chamber wider seems to alter aqueous humor circulation and drainage and additional trabeculectomy seems to play limited role in this process.

Intraocular pressure by time in two groups

Reduction in IOP at different follow-up periods suggests that during the first 8 weeks after surgery, the IOP declines considerably and then stabilizes and these achievements were similar in both groups. Paul et al.[17] also found similar results.

Need for antiglaucoma medication

Two patients in PE group required antiglaucoma medication in the immediate postoperative period. This could be because of postoperative inflammation in this group. Whereas in PT Group one patient required antiglaucoma medication at 6 months and 12 months follow-up due to late bleb scarring.

Findings in contrast to the present study

Unlike our results, Tham et al.[14] showed that combined PT has a clear advantage over “phacoemulsification alone,” when the mean number of topical antiglaucoma drugs needed is considered. A decrease in antiglaucoma medications has a positive effect on the quality of life by decreasing the cost, medication-related complications, and compliance.

Complications in phacoemulsification and phacotrabeculectomy

There was 1 case with wound leak in PT group which required resuturing and 2 patients with bleb scarring for which bleb needling with injection of 5-Fluorouracil was done. The rate of complications was low in PE than in PT group. These results were similar to the studies conducted earlier.[1417] These studies also showed the postoperative complications to be higher in PT group. There was no posterior segment complication noted postoperatively in our study.

Vision after phacoemulsification and phacotrabeculectomy

Shams and Foster[18] found that lens extraction in angle-closure glaucoma seems to have a beneficial effect on the BCVA. Tow et al.[19] and Jimmy et al.[20] who studied the combined effect of PT on angle-closure glaucoma found similar result on improvement in visual acuity.

Widening of angle of anterior chamber after phacoemulsification and phacotrabeculectomy

In phacoemulsification group, number of patients with only Schwalbe's line seen preoperatively was 36 and at 12-month follow-up, this was 10. The number of patients with visible anterior trabecular meshwork preoperatively was 10- and at 12-month follow-up, this was 36. There was significant angle widening post phacoemulsification (P < 0.001). These results are in accordance with the studies conducted by Dada et al.,[21] Hayashi et al.,[22] Pereira et al.,[23] and Nonaka et al.[24] who have studied the angle changes by ultrasound biomicroscopy. Huang et al.[25] found similar changes in the angle of the anterior chamber with anterior segment optical coherence tomography.

In PT group, number of patients with only Schwalbe's line seen preoperatively was 23 and at 12-month follow-up, this was 15. The number of patients with anterior trabecular meshwork preoperatively was 22 and at 12-month follow-up, this was 30. This shows significant angle widening post-PT (P < 0.001). The angle widening in the two groups at 12-month follow-up was similar (P = 0.827). This is consistent with the studies conducted by Tham et al.[14] The widening of angle of anterior chamber by removal of lens in all cases of chronic angle-closure glaucoma explains similar outcomes in different studies.

Clinical implications

For the subgroup of patients with nonsevere PACG with coexisting cataract who have undergone laser iridotomy, there are two options that can be considered, phacoemulsification with a possible stoppage of antiglaucoma medicines or PT which would eliminate the need of antiglaucoma medicines. This study aims at comparing safety and efficacy of the above two surgeries. The results suggest Phacoemulsification alone is safe and effective for IOP control and reduces the need for postoperative glaucoma medications and has lesser complications when compared to PT. Studies with outcomes longer than 1 year are recommended to further confirm the safety and efficacy of PE in the management of chronic angle-closure glaucoma with cataract.

Conclusion

We conclude that phacoemulsification is equally efficacious in terms of IOP control and visual recovery as PT with better safety and lesser postoperative complications. Cataract extraction may suffice as primary treatment for nonsevere PACG eyes with coexisting cataract.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.