Purpose
To present the 4-year follow-up results in the surgical treatment of hypotony following trabeculectomy with mitomycin C in glaucoma patients with additional flap sutures.
Design
Retrospective interventional case series.
Methods
Since 2006, 53 patients with hypotony maculopathy attributable to overfiltration following glaucoma surgery (trabeculectomy with mitomycin C) were included in this institutional study. We were able to follow up intraocular pressure (IOP) and distance-corrected visual acuity in 33 (62%) over 4 years, whereas all were followed over 2 years. To elevate IOP, we placed tangential transconjunctival sutures through the scleral flap and connected them to the adjacent sclera in all 53 patients.
Results
Mean IOP prior to surgery was 3.55 mm Hg (± 2.05; range 0-8 mm Hg), 20.08 mm Hg (± 12.48) on the first postoperative day, 10.69 mm Hg (± 4.73) after 1 month, 10.12 mm Hg (± 3.95) after 6 months, 10.42 mm Hg (± 4.17) after 2 years, and 9.5 mm Hg (± 3.93) after 4 years. Mean visual acuity (VA) improved from 0.8 logarithm of minimal angle of resolution (logMAR) preoperatively to 0.5 after 1 month, and remained stable after 6 months at 0.3. Macular folds resolved in all patients and choroidal detachment in 51 patients (96%) after 6 months. IOP increase and vision improvement were statistically significant (<.05).
Conclusion
Even 4 years after resuturing of the scleral flap through the intact conjunctiva, there is evidence that this surgical method is an effective and simple technique to treat hypotony maculopathy after glaucoma surgery.
Low intraocular pressure (IOP) attributable to overfiltration following trabeculectomy with mitomycin C is a common early postoperative complication, ranging from 1% to 18% of cases. Worsening visual acuity (VA) is attributable to corneal decompensation, flat anterior chamber, macular or choroidal folds, or detachment and decrease of axial lengths. If conservative methods such as the placement of bandage contact lenses or pressure patching, or use of acetazolamide to reduce outflow in the early postoperative period, are unsuccessful in managing hypotonic symptoms, transconjunctival flap sutures have the potential to preserve the flap and raise IOP rapidly. Other surgical techniques, such as reopening the conjunctiva and resuturing the scleral flap or patch with sclera, often lead to bleb scarring and its destruction. Since 2006 we have used transconjunctival flap sutures with success in patients with hypotony maculopathy following trabeculectomy with mitomycin C. In the presence of overfiltering blebs, it is our primary means of surgical intervention if conservative methods have failed. We now present our 4-year follow-up results after transconjunctival resuturing of the scleral flap (ie, flap suturing).
Methods
All study procedures adhered to the recommendations of the Declaration of Helsinki. The data of 53 of our clinic’s patients were evaluated in an institutional, retrospective, interventional case series, with patients going back to 2006. The local ethics committee of Mainz (Rhineland-Palatinate) approved the retrospective review of patient data for this study. All patients gave informed consent for surgery. Data on patients who underwent additional flap sutures through the closed conjunctiva were used for analysis. Follow-up data were available in 33 patients over 2 years and in 20 patients over 4 years. Demographics of the study cohort are shown in Table 1 .
| Total no. of patients | 53 |
|---|---|
| Sex | |
| Male | 27 |
| Female | 26 |
| Age (y) a | 63 (26-86) |
| Diagnosis (n) | |
| POAG | 23 |
| PEX | 19 |
| Cong-GL | 6 |
| NTG | 2 |
| PDG | 2 |
| Sec-GL | 1 |
| Time after trabeculectomy (mo) a | 2 (0.5-15) |
| Number of applied sutures a | 4 (2-10) |
The definition of hypotony is not standardized, so we adapted the position of Schubert in 1996, who stated that “clinical hypotony may be the variably low pressure that, in an individual eye, leads to loss of function and tissue changes over time.” Those could be a loss of VA, corneal decompensation, flat anterior chamber, macular or choroidal striae, choroidal detachment, or decrease of axial bulbous lengths. Patients underwent surgery if they presented postsurgical hypotony with low pressure and/or morphologic signs of hypotony. Trabeculectomy was augmented with mitomycin C in all patients. No bleb leakage was found, but all the patients had overfiltration. Retrospectively, we defined a successfull surgical outcome as achievement of a stable increase in VA compared with VA prior to additional flap sutures.
Twenty-three of the 53 included patients (43%) had primary open-angle glaucoma, 19 (36%) had pseudoexfoliative glaucoma, 6 (11%) congenital/juvenile glaucoma, 2 (4%) normal-tension glaucoma, 2 (4%) pigment dispersion glaucoma, and 1 (2%) secondary glaucoma.
All patients’ data were collected if available preoperatively and on the first and seventh postoperative day. They were then routinely examined after 1, 3, and 6 months, then annually. Collected data of VA, slit-lamp biomicroscopy, intraocular pressure measurement with Goldmann applanation tonometry, and fundoscopy through dilated pupils were used for analysis.
Surgery was performed 2 months after trabeculectomy (mean; range 0.5-15 months). Flap suturing was carried out using topical anesthesia with tetracaine 1% eye drops (Pharmacy of the University of Mainz, Germany). After disinfection with 1% povidone-iodine solution (Braun, Melsungen, Germany) and intended depression of gaze, the sclera flap margins were located. A 10-0 nylon on a cutting needle (Type CU-8, Circle: Bi-Curve; Alcon, Freiburg, Switzerland) was used and several sutures (mean 4, range 2-10) were stitched through the intact conjunctiva and tangentially into (not through) the scleral flap, readapted with the adjacent sclera, and knotted tightly over the conjunctiva. A tight suture was intended to elevate the postoperative IOP to flatten the macular folds (“ironing” effect). During the following days the suture moves into the conjunctiva and penetrates the tissue. This leads to a slow drop in IOP via suture relaxation in the days following surgery.
We used descriptive statistics: means, standard deviation, median, and range. A P value less than .05 was considered significant. Microsoft Excel 8.6 (Microsoft, Redmond, Washington, USA) and SPSS for Windows (version 16.1; SPSS Inc, Chicago, Illinois, USA) were used for the analysis.
Results
The mean IOP and VA response to the treatment are shown in Table 2 . Mean IOP before surgery was 3.55 mm Hg (± 2.05; range 0-8 mm Hg); IOP increased significantly ( P < .05) to 20.08 (± 12.48) on day 1 after surgery and dropped to 12.04 mm Hg (± 6.97) on day 7, stabilizing to 10.69 mm Hg (± 4.73) 1 month after surgery, to 9.87 mm Hg (± 3.91) after 3 months, and to 10.12 mm Hg (± 3.95) after 6 months. After 1 year, mean IOP was 9.85 mm Hg (± 3.97); mean IOP was 10.42 mm Hg (± 4.17) after 2 years, 9.74 mm Hg (± 3.8) after 3 years, and 9.5 mm Hg (± 3.93) after 4 years ( Figure 1 ).
| Prior FS | After FS | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1 d | 7 d | 1 m | 3 m | 6 m | 1 y | 2 y | 3 y | 4 y | ||
| Mean IOP (mm Hg) (standard deviation) | 3.55 (± 2.05) | 20.08 (± 12.48) | 12.04 (± 6.97) | 10.69 (± 4.73) | 9.87 (± 3.91) | 10.12 (± 3.95) | 9.85 (± 3.97) | 10.42 (± 4.17) | 9.74 (± 3.8) | 9.5 (± 3.93) |
| Mean VA (logMAR) | 0.8 | 0.7 | 0.6 | 0.5 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 |
| No. of patients | 53 | 50 | 49 | 52 | 52 | 51 | 53 | 53 | 45 | 33 |
Nine patients required 2 or more flap suture applications because of failure to show an increase in IOP or because of a renewed low pressure after an initial improvement from flap suturing. In 4 patients, this procedure was combined with autologous blood injection. One patient required autologous blood injection 1.5 years after the second flap suture application because of a new decrease in IOP. Only 1 patient needed flap revision with reopening of the conjunctiva and scleral flap resuturing with dura patch graft stitching because of fistulation after the second flap suture application and additional autologous blood injection.
Ten patients required laser suture lyses (or suture capture with Vannas scissors) because of hypertony after flap suture application, some of them combined with subconjunctival application of 5-fluorouracil.
Mean VA before glaucoma surgery (trabeculectomy with mitomycin C) was 0.3 logarithm of minimal angle of resolution (logMAR), dropping to 0.8 logMAR because of hypotony maculopathy prior to flap sutures. Vision improved to 0.6 logMAR after 1 week and to 0.5 logMAR after 1 month. Mean VA after 3 months was 0.3 logMAR, remaining stable 4 years after surgery.
At the 2-year follow-up, the VA of 45 of 53 patients (85%) of those who had received additional flap sutures was better than their preoperative VA. The VA of 8 patients remained unchanged, but no patient’s vision worsened. In 30 of 53 patients (56%), VA improved significantly ( P < .05) to preoperative values (before primary trabeculectomy) after 2 years, while 10 patients’ vision decreased slightly (minus 1 line) and 13 patients’ vision worsened markedly (2 or more lines). After 4 years, 20 of 33 patients (61%) had regained their original VA before trabeculectomy ( Figure 2 ).
Mean duration between onset of hypotony and flap suturing was 1.4 months (range 0.2-27 months). The outcome of IOP and VA in patients with short-term hypotony (duration <4 months) was not significantly different from long-term hypotony ( P < .05). In patients with long-term hypotony more additional interventions were necessary, such as autologous blood injection (3 patients) or surgical flap revision (1 patient).
The course and regression of hypotony maculopathy symptoms after transconjunctival flap suturing are illustrated in Table 3 . Macular folds existed in 27 patients preoperatively and disappeared in all patients after flap suturing surgery (4-year follow-up). Ten patients suffered from peripheral choroidal detachment, which disappeared in all patients after 1 year. Shallow anterior chamber deepened in all patients immediately after surgery and corneal Descemet folds remained no longer than 7 days in all patients.
