Preoperative prognostic factors for macular hole surgery: Which is better?

AIM: This study aims to evaluate the prognostic factors of different optical coherence tomography (OCT) parameters as well as the tamponade used in surgery, on postoperative anatomical and functional success.
METHODS: Twenty-nine eyes of 27 patients were included in this study. A three-port 23-gauge pars plana vitrectomy was performed on all eyes with peeling of the internal limiting membrane by visualization with brilliant blue dye by the same surgeon (E.U). Apical diameter (AD), base diameter (BD), and height (H) were manually measured by the same retina specialist (E.U) with using the software on OCT machine. Macular hole index (MHI), tractional hole index, diameter hole index, and macular hole volume (MHV) were calculated. The correlation between predictive factors and postoperative best corrected visual acuity (BCVA) was evaluated.
RESULTS: A statistically significant positive correlation was observed between preoperative BCVA, AD, BD, MHV, and postoperative BCVA scores. A statistically significant negative correlation was observed between preoperative MHI and postoperative BCVA scores (r = -0.676, P = 0.001). The strongest positive correlation was between BD and postoperative BCVA (logMAR) (r = 0.732, P = 0.001). The visual improvement was statistically better in patients treated with C3F8 than SF6.
CONCLUSION: BD and MHV could be used as a strong predictive OCT parameters of postoperative functional success.

Introduction

Idiopathic macular hole is one of the most common forms of macular hole (MH), occurs in the macular area of a healthy eye, usually in patients over 50 years old and could cause marked reduction in vision.[1234] Anteroposterior forces by vitreofoveal and tangential tractions cause MH formation.[1234] The first successful surgery of MH with pars plana vitrectomy (PPV) was performed by Kelly and Wendel in 1991.[5] Ever since, there have been several advances in vitrectomy techniques to achieve better anatomical and functional results.[6789] Despite these advances, the increase in visual acuity (VA) of patients may be limited after anatomical closure of the hole.[110]

Spectral-domain optical coherence tomography (SD-OCT) is a noncontact, noninvasive, and laser interferometry technique. In vivo high-resolution cross-sectional images could be obtained by using SD-OCT. SD-OCT imaging could also give us a detailed foveal and vitreous microstructure and MH dimensions. Therefore, studies using OCT have been explored to define the factors that may influence visual improvement.[11121314151617] The parameters such as MH index (MHI), tractional hole index (THI), hole form factor (HFF: left arm + right arm/base diameter [BD]), and MH volume (MHV) were used to predict the postoperative visual function.[111213181920]

In addition, the effectiveness of tamponade and staining methods used during the surgery has also been studied by different study groups.[2122]

In this study, we aimed to evaluate the prognostic factors of different dimensional and volumetric factors as well as the tamponade used in surgery, on postoperative anatomical and functional success.

Methods

A retrospective and comparative study was designed to evaluate the prognostic effects of different factors on patients treated for MH. The study protocol was approved by the local ethics committee. The study was designed in accordance with the Declaration of Helsinki. Before the surgery was performed, informed patient consent was taken from all patients about the complications of MH surgery.

Medical charts of patients with a diagnosis of large full-thickness MH and treated with PPV combined with internal limiting membrane (ILM) peeling and intraocular gas tamponade in our Retina Unit between January 2011 and January 2017 were retrospectively reviewed in this study.

Eyes diagnosed as idiopathic Stage 2–4 MHs with at least 6 months postoperative follow-up were included in this study. Eyes with high myopia (≥ minus 6D) and history of previous PPV were excluded from the present study.

Demographic data including age and gender, additionally the duration of symptoms, and the involved eye were evaluated for each patient. Preoperative best-corrected VA (BCVA) assessment with the Snellen VA chart, slit lamp examination of the anterior segment, IOP measurement, and a dilated fundus examination were performed. A MH was diagnosed by slit lamp biomicroscopy with a 90D lens and confirmed by SD-OCT (Optovue OCT V 5.1, RTVue 100-2; Optovue, Fremont, CA, USA).

A total of 30 eyes of 28 patients fulfilled the inclusion criteria and were included in this study.

All surgeries were performed by the same surgeon (E.U) under retrobulbar local anesthesia. Before MH surgery, phacoemulsification was done if a cataract was present in cases of combined surgery. A 3-port 23-gauge PPV was performed on all eyes. After applying core vitrectomy through triamcinolone acetonide (10 mg/ml), the posterior vitreous detachment was induced with a vitrectomy probe around the optic disc. The peripheral vitreous was then removed with careful inspection of the retinal periphery. If present, epiretinal membrane peeling was performed. The ILM was stripped within a fovea-centered circular area of two-three optic disc diameters by visualization with brilliant blue dye 0.05% (Ocublue plus, brilliant blue G solution, aurolab). Gas (14% C3F8 or 20% SF6) was used as an intraocular tamponade. A face-down position was advised for 1 week.

Postoperatively, topical steroids and antibiotics were prescribed and gradually tapered. Patients were examined on day 1, at 1 weeks, 4 weeks, 3 months, and then at 6 months postoperatively. All the results of complete ophthalmological examinations, SD-OCT images taken during pre and postoperative visits, were reevaluated for each case.

Postoperative complications were documented when present.

Apical diameter (AD), BD, and height (H) were manually measured on the image of OCT by the same retina specialist (E.U) with using the software on OCT machine. AD was measured at the minimal extent of the hole. BD was measured at the level of the retinal pigment epithelium. H was measured at the greatest height of the hole from the retinal pigment epithelium to the vitreoretinal interface.

MHI, THI, and diameter hole index (DHI) were calculated as shown in Figure 1. MHI was defined as the ratio of the hole height to the BD visualized by cross-sectional OCT images.[13] DHI was described as the ratio of the AD of the MH to the BD.[12] THI was described as the ratio of the maximal height to the AD of the MH.[12]

Figure 1

Measurement of different optical coherence tomography parameters and calculation of macular hole volume

MHV was described as space under the imaginary line defined as AD which was drawn at the minimal extent of the hole [Figure 1]. As this space is a truncated cone, MHV was calculated with the formula of a truncated cone [Figure 1]. We used the widest two-dimensional cross-sectional SD-OCT image of all MHs included in this study.

BCVA was recorded as a Snellen VA and converted to (LogMAR) logarithm of the minimum angle of resolution or recognition for statistical analysis.

Statistical Package for the Social Sciences (SPSS) version 20.0 (IBM, New York, USA) software was used for all statistical analyses. Descriptive statistics are presented as minimum, maximum, and mean ± standard deviation. The normality of data was checked using the Kolmogorov–Smirnov test. Mann–Whitney U-test and independent samples t-test were used for independent samples. Wilcoxon signed-rank test was used for related samples. P < 0.05 was accepted as statistically significant. The relation between MHI, THI, DHI, MHV, and postoperative BCVA was evaluated with using Pearson's correlation coefficient test.

Results

Twenty-nine eyes of 27 patients fulfilled the inclusion criteria and were included in this study. The demographic characteristics of patients and the mean follow-up time are shown in Table 1.

Table 1

Demographic characteristics

Parameters	Values	Range
Mean age (year)	67.6±11.5	26-78
Patients/eye	27/29
Female/male	13/14
Mean follow-up time (m)	13.5±11.4	6-41
Preoperative phakia /pseudophakia	25/4
PPV/phaco + PPV	11 (3 SF6-8 C3F8)/18 (3 SF6-15 C3F8)
C3F8/SF6	23/6
History of glaucoma	6

PPV: Pars plana vitrectomy, phaco: Phacoemulsification cataract surgery

Postoperative BCVA was significantly better than preoperative BCVA [Table 2]. Twenty eyes of 30 (66.6%) had two or more lines improvement in BCVA. Seven eyes (23.3%) had one line improvement. Two eyes (6.6%) had no improvement. Preoperative and postoperative IOP values were shown in Table 2.

Table 2

Comparison of pre- and post-operative best-corrected visual acuity and intraocular pressure values

Parameters	Preoperative	Postoperative	P
BCVA (logMAR)	1.32±0.61	0.78±0.44	0.007
IOP	16.86±3.32	17.03±3.32	0.317

Wilcoxon signed-ranks test. BCVA: Best-corrected visual acuity, LogMAR: Logarithm of the minimum angle of resolution, IOP: Intraocular pressure

Mean AD, BD, height, and MHV were found as 451.8 ± 204.7 μ (190–810 μ), 941.7 ± 369.7 μ (501–1750 μ), 253.2 ± 99.0 μ (70–460 μ), and 0.074 ± 0.063 mm3 (0.219–0.0090 mm3), respectively. In addition, THI, MHI, and DHI were calculated as 0.66 ± 0.39 (0.15–1.67), 0.30 ± 0.16 (0.09–0.58), and 0.48 ± 0.13 (0.20–0.77), respectively.

We compared two different tamponades, C3F8 and SF6 in terms of visual improvement. The visual improvement was statistically better in patients treated with C3F8 than SF6 (P = 0.02) [Table 3]. The higher number of patients treated with phaco + PPV in C3F8 group (15 eyes in C3F8 group and 3 eyes in SF6 group) could have caused this result [Table 1].

Table 3

Comparison of visual ımprovement between C3F8 and SF6

Parameters	C3F8	SF6	P
Visual improvement (logMAR)	−0.36±0.54	0.063±0.42	0.02*
PPV + phaco/PPV	15/8	3/3	0.046**

*Mann-Whitney U-test, **Chi square. PPV: Pars plana vitrectomy, phaco: Phacoemulsification cataract surgery, LogMAR: Logarithm of the minimum angle of resolution

The associations between MH parameters and postoperative BCVA were analyzed using Pearson's correlation coefficient test [Table 4].

Table 4

Pearson correlation analysis between postoperative best-corrected visual acuity (logarithm of the minimum angle of resolution) and macular hole parameters

Parameters	R	P
Follow-up	−0.276	0.236
Postoperative CMT	−0.245	0.380
Height	−0.165	0.375
DHI	−0.182	0.340
THI	−0.442	0.015
Preoperative BCVA	0.475	0.001
MHV	0.636	0.001
MHI	−0.676	0.001
BD	0.732	0.001
AD	0.575	0.001

BCVA: Best-corrected visual acuity, MH: Macular hole, CMT: Central macular thickness AD: Apical diameter, BD: Base diameter, MHV: Macular hole volume, MHI: Macular hole index, THI: Tractional hole index, DHI: Diameter hole index

A statistically significant positive correlation was observed between preoperative BCVA, AD, BD, MHV, and postoperative BCVA scores. A statistically significant negative correlation was observed between preoperative MHI, preoperative THI, and postoperative BCVA scores (r = −0.675, P = 0.001, r = −0.440, P = 0.015). The strongest positive correlation was between BD and postoperative BCVA (logMAR) (r = 0.73, P = 0.001) [Table 4].

We did not observe any recurrences in any of our cases after the mean follow-up of 13.5 ± 11.4 (range, 6–41) months.

Discussion

Owing to recent advances in MH surgery, the anatomical closure rates of the hole were improved;[6789] however, the increase in VA of patients may be limited.[110] Preoperative SD-OCT parameters allowed better estimation of postoperative visual function;[111314] however, there was limited information for correlation of volumetric features and functional success.[18192023]

In the present study, our first aim was to determine the best SD-OCT parameters to estimate postoperative visual success. We observed a significant correlation between AD, BD, MHV, MHI, THI, and postoperative BCVA scores. In addition, according to our results, we found that the strongest correlation was between BD, MHV, and postoperative BCVA (LogMAR). On the other hand, according to the correlation analysis, postoperative CMT, preoperative height, postoperative follow-up time, and DHI did not affect the postoperative BCVA. Previously, a negative correlation was shown between postoperative BCVA and BD of hole and height of hole.[15] Similarly, Ruiz-Moreno et al. showed that AD, BD, THI, and MHI correlated significantly with postoperative BCVA;[12] however, height and DHI was not correlated with postoperative BCVA in their study. And also, Ullrich et al.[11] reported a negative correlation between BD, AD, and postoperative visual prognosis, similar to our study. Hence, we thought that AD, BD, MHI, and THI could be used as significant predictors.

There were only a few numbers of studies about correlation between postoperative BCVA and the MHV. Xu et al.[23] reported a significant correlation between base area, MHV, and 6-month postoperative BCVA. Moreover, base area, BD, top area, AD, height, and MHV were found as correlated with baseline BCVA.[23] Pilli et al.[19] presented a close correlation between inner macular volume and BCVA. On the other hand, Ozturk et al.[18] reported that although a correlation between MHV and postoperative CMT was observed, there was no correlation between MHV and postoperative BCVA. Geng et al.[20] defined area ratio factor (ARF, body surface area/bottom base area) and volume ratio factor (VRF, inferior volume/all volume) and they proposed that the parameter ARF could effectively predict postoperative visual success. They did not observe a correlation between VRF and postoperative BCVA. In the present study, we defined a significant correlation between MHV and postoperative BCVA similarly Xu et al.[23] and Pilli et al.[19] Moreover, in the present study, MHV was observed as the second best predictor of postoperative visual success. Using different software and models of OCT machines could be the most important reason of inconsistency between these studies.

In addition, we defined a correlation between preoperative and postoperative BCVA consistent with previous literature.[18]

We compare two different tamponades, C3F8 and SF6 in terms of visual improvement.

We found that the visual improvement was statistically better in patients treated with C3F8 than SF6. A limited number of patients treated with SF6 tamponade and the higher number of patients treated with phaco + PPV in C3F8 group could have caused this result.

We could not compare two different tamponades in terms of hole closure rate because our anatomical success rate was 100% for both tamponades. Unlike our study, Modi et al.[21] presented no differences between SF6 and C3F8 in terms of visual improvement and hole closure. They reported a decreased incidence of cataract and ocular hypertension with SF6. They suggested C3F8 for failed primary surgery.

The lack of real-time three-dimensional volumetric analysis was the most important limitation factor of our study. Hence, our calculated MHV was not a certain result; it was an estimated value. Another important limiting factor was the relatively small sample size.

Conclusion

We proposed BD and MHV as a strong predictive OCT parameters of postoperative functional success, especially for clinics using OCT. In addition, we observed preoperative BCVA as an important examination factor affecting postoperative BCVA. However, due to the inconsistency between different reports, a long-term prospective study with a large sample is needed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.