A Descriptive Study on Visual Outcome and Intraocular Pressure Control after Trabeculectomy with Manual Small Incision Cataract Surgery in Patients with Glaucoma and Cataract.

Context: Glaucoma is a optic neuropathy having multifactorial causes. Both cataract and glaucoma condition can influence management of the one another. Aims: To know the visual outcome and intraocular pressure control after combined trabeculectomy in patients with glaucoma and cataract. Settings and Design: It was a descriptive interventional study done for two years. All patients diagnosed to have significant cataract and diagnosed glaucoma were included in study. Methods and Material: After taking consent, combined surgery was performed and post-op follow up was done on 1st postoperative day and then on 1st week, 2weeks, 4weeks, 6weeks, 8weeks and 6 months. All parameters assessed and tabulated for statistical analysis.
Results: Mean age of subjects was 59 years. 46.7% were males. Most of the patients (73.4%) were diagnosed as POAG. 26.7% were having PACG. Pre-operatively, 7 patients had vision better than 6/36. 13 patients had 6/36 and 10 patients had less than 6/36. At 6 weeks postoperatively, 76.7% had vision 6/9 or better, 16.7% had between 6/12 to 6/18, 6.7% less than 6/18. Mean IOP, Preoperatively among POAG and PACG was 19.90 and 33.25mmHg. Among POAG, Postoperatively at 6weeks, 8week, and 6months, IOP was 13.81, 13.91 and 12.72mmHg respectively. Postoperatively at 6weeks, 8week, and 6months, IOP was 19.75, 18.00 and 17.25mmHg in case of PACG. Conclusions: The study has showed the postoperative visual outcome and control of intraocular pressure is better with combined trabeculectomy with cataract surgery but still patients should be individualised according to their presentation. Copyright:

BACKGROUND

The advent of combined surgery has been a saviour in cases with cataract and glaucoma, specially in developing countries where socioeconomic status and health services are not par for patients to have frequent follow up. The need for only one surgery for the disease (with decreased frequency of follow up) and no need for dependency of antiglaucoma medications prove to be a winner in poor countries. But at the same time, the need to evaluate the quality of health services offered and the progression of this blinding disease is also important so that it can be assessed and improved in the near future.

INTRODUCTION

The leading causes of blindness worldwide are cataract and glaucoma, next to refractive errors.[1] Studies have shown that in India, there are approximately more than 11 million glaucoma patients.[2]

Glaucoma is an optic neuropathy having multifactorial causes, among which intraocular pressure (IOP) is found to be the most linkable cause.[3] Reducing intraocular pressure has shown to slow the progression of this blinding disease.[45] Trabeculectomy is one such surgical procedure which helps in decreasing and maintaining the intraocular pressure.

Cataract and glaucoma can influence the management of one another. Lens changes can mimic visual field loss, reduce visual acuity, and narrow the drainage angle. In addition, prior glaucoma surgery leads to a clinically significant acceleration of cataract formation in the years following trabeculectomy.[6]

Thus, each of these diseases must be considered when treating the other. Only trabeculectomy may not be able to achieve the target pressure; combining it with cataract surgery will achieve the goal for a longer duration.[7] A single procedure, reduced time taken for the patient's recovery, reduced cost, longer IOP control, and decreased chances of wipe-out phenomenon makes the combined procedure more preferable.[58]

Other important things to keep in mind include minimizing surgical trauma and risk, and ensuring that the procedure is cost effective. With these parameters determining the choice of surgery, it is evident that combined procedures are fast gaining popularity. (cataract and coexistent glaucoma: a therapeutic dilemma)

Thus this prospective study was undertaken to study the visual outcome and intraocular pressure control after combined manual small incision cataract surgery and trabeculectomy in patients with cataract and glaucoma.

METHODOLOGY

It was a descriptive study done for a duration of two years. Patients with visually significant cataract with primary open-angle glaucoma (POAG) with uncontrolled IOP with maximally tolerated medical therapy, and patients with visually significant cataract with primary angle closure glaucoma (PACG) with >180 peripheral anterior synechiae were included in the study. Patients with mature cataract where the disc could not be visualized, traumatic cataract, complicated cataract, patients with subluxated lens, those with intraocular pathology (corneal opacity, ARMD, optic atrophy, CRVO, etc.) other than cataract and glaucoma, patients who had undergone argon laser trabeculoplasty, and patients who had undergone intraocular surgery were excluded from study.

METHOD OF STUDY

Detailed history and eye examination was done in all the cases, meeting the objectives of the study after a written informed consent. IOP was recorded with a Goldmann applanation tonometer. The number and class of antiglaucoma drugs were noted. A preoperative keratometry (Bausch and lomb) and biometry (A-scan) was done for calculation of intraocular lens (IOL) power. All patients were taken up for surgery after selection criteria was fulfilled.

Intraoperative

After removing conjunctival flap, a rectangular flap of (4 × 5 mm) 2/3 to ½ scleral thickness and around 6–8 mm in size was raised superiorly 2 mm away from limbus. Scleral flap was dissected forward until at least 1 mm of bluish-grey zone was exposed. Then an inner block of trabecular tissue (1 × 2 mm) was excised with Kelly's punch and then broad-based peripheral iridectomy was performed.

Scleral incision was dissected with crescent knife. Scleral tunnel with side pockets extending about 1–2 mm into clear cornea was made. Side port was done with 15° Lancet tip blade. Air was injected through the side port. Trypan blue was used to stain the capsule and chamber formed with viscoelastics. Entry into anterior chamber was made using 2.8/3.2 mm keratome and extended on either side.

A continuous curvilinear capsulorhexis was performed. Hydrodissection was done and nucleus prolapsed into AC and delivered out by visco expression technique. Then cortical matter was aspirated by Simcoe cannula. PCIOL was implanted and remaining visco was removed.

The scleral flap was sutured with interrupted 10-0 nylon suture. Conjunctival flap also sutured with interrupted sutures. Patency was checked by injecting BSS into the anterior chamber and formation of Bleb. Then stromal hydration was done. Subconjunctival injection of dexamethasone and gentamycin was given. Eye was then padded.

Post-op follow up was done on first postoperative day and thereafter after 1 week, 2 weeks, 4 weeks, 6 weeks, 8 weeks, and 6 months.

Statistical method used

Sample mean or median

Sample standard deviation

t test or sign test for single sample and related statistics with graph

Data was analyzed using R software

RESULTS

Mean age of the patients was 59.6 years. 6 (20%) were less than 50 years of age, 11 (36.7%) were between 51 and 60 years, 6 (20%) between 61 and 70 years, and 7 (7%) were over 70 years of age, with majority being in the 51–60 years age group.

PACG patients were of a younger age group in contrast to those in the POAG group. Of the 30 patients, 14 were males (46%) and 16 were females (54%). 18 patients underwent surgery of RE and 12 patients of LE. Among the 30 patients, 5 were known to be hypertensive, 5 were diabetics, 2 were asthmatic, and the remaining 18 had no systemic comorbidities. A majority of the patients (73.4%) were diagnosed with POAG and 26.7% with PACG.

Preoperatively, 2 patients had vision better than 6/9, 5 patients had 6/12 to 6/18, and 23 patients had less than 6/18. At 6 weeks postoperatively, 23 patients (76.7%) had vision 6/9 or better, 5 patients (16.7%) had between 6/12 to 6/18, 2 patients (6.7%) less than 6/18.

At 6 months postoperatively, 21 patients (70%) had vision 6/9 or better, 7 patients (23.3%) had between 6/12 to 6/18, and 2 patients (6.7%) less than 6/18. Mean preop IOP in POAG and PACG patients were 20 mmHg and 33.25 mmHg, respectively.

Preoperatively 15 patients were using single topical anti-glaucoma drug, that is, timolol (8 patients) and travoprost (7 patients), and 15 patients were on combination drugs. Among POAG, postoperatively at 6 weeks, 8 weeks, and 6 months was 13.81 mmHg, 13.91 mmHg, and 12.72 mmHg, respectively. PACG, postoperatively, at 6 weeks, 8 weeks, and 6 months was 19.75 mmHg, 18.00 mmHg, and 17.25 mmHg respectively.

13 patients had type 1 bleb (diffuse, slightly elevated, avascular) 9 had type 2 (discrete, elevated, avascular) and 3 had type 3 bleb (flat, avascular)

Intraoperatively, 5 patients had complication, 2 had hyphema, and 3 had Descemet's membrane detachment (DMD). In 25 patients, no complications were noted.

Immediate postoperative complications included hyphema in 1 patient, iritis in 6, striate keratopathy in 5, shallow AC in 2, and in the remaining 16 patients, no complications were noted.

DISCUSSION

The study included 30 patients diagnosed with both cataract and glaucoma. Mean age of the patients in the study was 59 years. 6 (20%) were less than 50 years of age, 11 (36.7%) were between 51 and 60 years, 6 (20%) between 61 and 70 years, and 7 (7%) were over 70 years of age with majority being from the 51–60 age group.

In a study conducted by Wedrich A, et al.[9] and Usha et al.,[10] the mean age of patients who underwent combined surgery was 76.40 years and 68.04 years, respectively. Age is a major risk factor for glaucoma; in other words, incidence of glaucoma increases with age.

Majority (80%) of the patients had moderate glaucomatous cupping (CDR 0.7 and 0.8). 43.3% had CDR of 0.7, 36.7% had 0.8, while the remaining 6 patients had CDR of 0.6 CDR (6.7%) and 0.9 (13.3%). Most of the POAG patients had advanced cupping when compared to PACG patients. In a study conducted by Singh P et al.,[11] 77.8% had 0.9–0.95 CDR, 8.9% had 0.8—0.85 CDR. In study by Usha et al.,[10] 60% had CDR >0.9, and 29% had 0.75–0.85 CDR.

On gonioscopy, 22 patients showed open angles and were diagnosed to have POAG, 8 patients showed closed angles with peripheral anterior synechiae of more than 270° and were diagnosed with PACG.

Mean preoperative IOP was 23.5 mmHg, ranging from 16–36 mmHg. 16 patients had IOP less than 20 mmHg, 8 patients had between 21 and 30 mmHg, and 6 patients had more than 30 mmHg. Mean preoperative IOP in POAG and PACG patients was 20 mmHg and 33.25 mmHg, respectively. PACG patients had higher mean preoperative IOP in comparison to POAG patients.

Mean IOP, preoperatively, was 23.47 mmHg, and postoperatively at 6 weeks, 8 weeks, and 6 months was 15.4 mmHg, 15 mmHg and 14 mmHg, respectively; reduction in mean IOP was statistically significant. Among POAG patients, the mean preoperative IOP was 19.90 mmHg, and postoperatively at 6 weeks, 8 week, and 6 months, it was 13.81 mmHg, 13.91 mmHg, and 12.72 mmHg respectively. Among PACG patients, mean preoperative IOP was 33.25 mmHg, and postoperatively at 6 weeks, 8 weeks, and 6 months, it was 19.75 mmHg, 18.00 mmHg, and 17.25 mmHg, respectively.

The results were comparable to a study by Wedrich A et al. where the mean preoperative IOP was 21.2 ± 6.0 mmHg and postoperative IOP was 13.5 ± 2.1 mmHg. Christian Skorpik[12] also received similar results in which mean postoperative IOP was 20 mmHg or less. In a study by Tukaram Ranbaji Gitte et al., preoperative IOP was 40.33 mmHg and postoperative IOP was 14.71 mmHg on day 7 and day 40. Usha et al.[10] also observed that the mean postoperative IOP was less than 16 mmHg in combined procedure during 100% visits.

Preoperatively, 7 patients had vision better than 6/36, 13 patients had 6/36, and 10 patients had less than 6/36. At 6 weeks postoperatively, majority of the patients, that is, 23 patients (76.7%) had vision 6/9 or better, 5 (16.7%) had between 6/12 to 6/18, and 2 (6.7%) had less than 6/18. At 6 months postoperatively, 21 patients (70%) had vision 6/9 or better, 7 (23.3%) had between 6/12 and 6/18, and 2 (6.7%) had less than 6/18.

Singh P et al.[12] observed that 65.7% achieved BCVA 6/-6/18, 17.1% had 6/24 to 6/60 on 6th week follow up. 76% visual outcome of more than 6/18 was seen in a study done by Usha et al.[10]

All patients had functioning bleb at 6 months of follow up with different morphology, 13 patients had type 1 bleb (diffuse, slightly elevated, avascular), 9 had type 2 (discrete, elevated, avascular), and 3 had type 3 bleb (flat, avascular).

Intraoperatively, 5 patients had complications, 2 had hyphema, 3 had DMD which was managed conservatively, and the remaining 25 patients showed no complications.

Immediate postoperative complications included hyphema in 1 patient, iritis in 6 patients, striate keratopathy in 5 patients, shallow AC in 2 patients, and in remaining 16 patients, no complications were noted.

CONCLUSION

A combined cataract and filtering surgery may help an elderly person having cataract, living in a developing country and with financial constraints, to have faster visual recovery along with good glaucoma control.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.