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OCT helps predict macular hole surgery success
Smaller holes, as measured by OCT, were closed more consistently by surgery.
MUNICH — Preoperative measurement of macular hole size using optical coherence tomography can help predict the success of repairs as well as visual outcomes of surgery.
“Today pars plana vitrectomy and membrane peeling have become the standard procedure for closing macular holes. We sought to predict the role of OCT in diagnosing and staging, as well as in predicting the functional and anatomical outcome after macular hole surgery,” reported Prof. Dr. med. Anselm Kampik, MD, and colleagues in the British Journal of Ophthalmology.
Prof. Kampik, professor and chair of the department of ophthalmology at Ludwig-Maximilians-University, and colleagues conducted a prospective study of 94 consecutive patients with idiopathic full-thickness macular holes. Average age of the patients was 68 years, and more than 75% were women. Patients who had underlying macular diseases including macular degeneration or diabetic retinopathy were excluded from the study.
Researchers used a slit-lamp exam and OCT to determine the stage of the macular hole, the authors reported.
“The slit-lap exam was conducted according to the Gass classification. The results of this and OCT were compared,” they noted.
Slit lamp vs. OCT staging
Upon slit-lamp examination, eight eyes were classified with a stage 2 macular hole, 71 patients had stage 3, and 14 eyes were diagnosed with stage 4. Using OCT, four eyes were assigned a classification of stage 2 (three eyes consistent with slit-lamp examination), 29 eyes had grade 3 (23 consistent with slit lamp) and 40 eyes had grade 4 (six consistent), the authors said.
Visual acuity was measured preoperatively and again postoperatively at 6 weeks, 12 weeks, 6 months and 12 months.
“For statistical analysis, only the best corrected postoperative visual acuity achieved by each patient at one of these visits was used,” the authors explained.
To repair the macular hole, surgeons performed a standard three-port pars plana vitrectomy. The epiretinal and inner limiting membranes were peeled, and then a C2F6 gas tamponade was instilled. Patients were asked to maintain a prone position for 5 days postop. Anatomical success of the procedure was defined as flattening of the macular hole with no subretinal fluid present, the authors said.
Macular hole diameters
Using OCT, surgeons defined two macular hole diameters.
“The first diameter was measured at the level of the retinal pigment epithelium; this was called the base diameter. The second macular hole diameter defined with OCT was at the minimal extent of the hole, called minimum diameter,” the authors said.
They then calculated the hole form factor (HFF) according to previously published reports by Puliafito et al. They correlated the HFF and the diameter measurements with the patients’ postop visual acuity and visual improvement.
The researchers found a significant negative correlation between both the base (P = .016) and the minimum diameter (P = .002) of the macular hole and postop visual acuity.
“The better postoperative visual acuity positively correlated with a higher HFF value (P = .05). We found no correlation between postoperative gain in lines and HFF (P = .76) or with the base and minimum diameter (P = .19; P = .071),” they said.
Other results
Among the 13 eyes that failed to have anatomical closure after the first surgery, the base diameter and the minimum diameter of the hole were significantly larger than in the eyes that had immediate closure, the researchers found.
In all patients with HFF greater than 0.9 (n = 10) the macular hole was closed following one surgical approach, the authors said. However, in eyes with HFF 0.5 or less, the anatomical success rate after one operation was only 67% (n = 6).
“With respect to the correlation coefficient, r, the minimum diameter measured with OCT seems to be a better predictor than the HFF (minimum diameter r = –0.312; HFF r = 0.203),” they said.
“Besides better anatomical results compared to those of Puliafito and colleagues, we also found a significant correlation between HFF and anatomical success rate,” Prof. Kampik and colleagues noted. “A possible explanation for the higher success rate in our patients compared with those of Puliafito et al might be that eventual existing epiretinal membranes, including the inner limiting membrane, were removed during surgery in our series.”
The researchers concluded that preoperative OCT measurements seem to be of predictive value for the functional and anatomical outcome of macular hole surgery.
For Your Information:Reference:
- Prof. Dr. med. Anselm Kampik, MD, can be reached at the department of Ophthalmology, Ludwig-Maximilians-University, Mathildenstrasse 8, D-80336 Munich, Germany; +(49) 89-5160-3800; fax: +(49) 89-5160-4778; e-mail: Anselm.Kampik@ak-i.med.uni-muenchen.de.
- Ullrich S, Kampik A, et al. Macular hole size as a prognostic factor in macular hole surgery. Br J Ophthalmol. 2002;86:390-393.