To evaluate cross-sectional areas of conjunctivochalasis and tear meniscus using Fourier-Domain RTVue-100 optical coherence tomography (OCT) before and after conjunctival cauterization and to evaluate inter- and intraobserver reliability.
Prospective, nonrandomized, consecutive case study.
A total of 12 eyes of 7 patients with conjunctivochalasis (aged 56 to 87) were evaluated. After topical anesthesia, conjunctival cauterization was performed on the inferior bulbar conjunctiva. All patients underwent anterior segment OCT (AS-OCT) imaging prior to and 4 weeks after the procedure. Cross-sectional tear meniscus and conjunctivochalasis areas at 3 locations (nasal, center, and temporal areas) were measured in all patients.
Nonsignificant increases ( P = .177) in cross-sectional tear meniscus area as a whole (3 locations combined) were observed following cauterization. Cross-sectional conjunctivochalasis area measurements significantly decreased in all 3 locations after cauterization ( P < .001). Mean cross-sectional conjunctivochalasis area decreased from 0.247 ± 0.24 mm 2 to 0.054 ± 0.79 mm 2 . For 2 measurements of cross-sectional tear meniscus area by examiner 1, intraclass correlation coefficients ranged from 0.998 to 0.999. Among 2 examiners, Cronbach’s alpha reliability coefficients were as high as 0.993 and 0.997 before and after conjunctival cauterization. Regarding the cross-sectional conjunctivochalasis area measurements, intraclass correlation coefficient values were similar to those of the cross-sectional tear meniscus area, but Cronbach’s alpha reliability coefficients were slightly less.
This study indicates the AS-OCT is a useful and reproducible instrument to measure the cross-sectional area of conjunctiva prolapsing into the tear meniscus of patients with conjunctivochalasis. The method can monitor effectiveness of thermoreduction of conjunctivochalasis.
Optical coherence tomography (OCT), which was introduced in the early 1990s, is a noncontact imaging method that provides detailed cross-sectional images of biological tissues by measuring their optical reflections. OCT has been widely used clinically in ophthalmologic practice for a number of years. It has been a significant advance in diagnosis and monitoring treatment of vitreoretinal diseases such as age-related macular degeneration and macular edema, as well as glaucoma.
In recent years, OCT technology has evaluated the incorporation of spectral-domain (SD) imaging that offers significant advantages over the traditional time-domain (TD) OCT techniques, which include faster imaging speed, higher resolution, and better visualization. Simultaneously with these improvements, the utility of OCT in the ophthalmic practice has become more extended. For example, anterior segment OCT (AS-OCT), which provides high-resolution cross-sectional images of anterior segment structures, including anterior chamber angle, cornea, conjunctiva, and tear meniscus, has recently gained popularity.
AS-OCT has been reported to image conjunctival filtering blebs after trabeculectomy; however, there are no reports of using AS-OCT to diagnose conjunctivochalasis or monitor efficiency of surgical therapy for this condition. The goal of the present study was to evaluate cross-sectional conjunctivochalasis and tear meniscus areas using the Fourier-Domain RTVue-100 OCT before and after conjunctival cauterization in patients with moderate to severe conjunctival chalasis.
Material and Methods
Twelve eyes of 7 patients (2 male and 5 female) with conjunctivochalasis who did not respond to conventional medical therapies were evaluated in this prospective study. Patients with a history of previous conjunctival or lid surgery or any lid abnormalities such as ectropion, entropion, and trichiasis; contact lens use; or use of any eye drop up to 2 hours before the imaging were not included in the study. All patients had a complete anterior segment examination at each visit.
The procedure was performed by the same surgeon (S.C.P.) in all patients. After topical anesthesia (0.5% proparacaine ophthalmic solution [Accutome-R x , Bausch & Lomb Incorporated, Tampa, Florida, USA] and 4.0% lidocaine hydrochloride solution [Roxane Laboratories Inc, Columbus, Ohio, USA]) was instilled, redundant inferior bulbar conjunctiva was cauterized using a low-temperature handheld fine-tip thermocautery (Bovie Aaron Medical, St. Petersburg, Florida, USA). The redundant bulbar conjunctiva was grasped between the blades of a curved tying forceps and the captured tissue was cauterized down to forceps surface. Cautery was performed in a line from the lateral to medial canthus approximately 5 mm below the inferior limbus. Postoperatively, eyes were treated with 1% prednisolone acetate ophthalmic suspension (Pred Forte; Allergan, Inc., Irvine, California, USA) 4 times daily for the first week and twice daily in the second week.
Patients were asked to return for follow-up examination 1 month after the procedure. At this visit, besides routine ophthalmologic examination and AS-OCT imaging, continuity of the fluorescein-stained inferior tear meniscus and relief of irritation symptoms were also noted.
Anterior Segment Optical Coherence Tomography Measurements
All patients underwent AS-OCT imaging prior to the procedure and 4 weeks after the procedure. AS-OCT images including lower tear meniscus and conjunctivochalasis were carried out using RTVue-100 (Ver. 188.8.131.52; Optovue Inc, Fremont, California, USA) with a corneal adaptor by the same person (K.G.).
Two parameters were measured in all images: cross-sectional area of inferior tear meniscus and conjunctivochalasis.
Measurement of the Cross-Sectional Area of Lower Tear Meniscus and Conjunctivochalasis
The lower tear meniscus and conjunctiva in each eye was imaged by vertical scans centered on the inferior cornea and the lower eyelid. The system takes 26 000 axial scans per second and has a 5-μm axial resolution and transverse resolution of 15 μm. The Cornea–Anterior Module (CAM) is additional software on the device, for anterior segment imaging. Two lens adapters with short-CAM (10 mm, higher magnitude) and long-CAM (13 mm, wide field) are available for corneal and anterior segment examination. In the current study, the images were taken after connecting the long-CAM lens to the RTVue.
Examination was performed by positioning the patient’s chin on the chin rest and the forehead against the headrest, asking the patient to look straight ahead after turning off the room light as recommended. No topical anesthesia or lubricating drops were used. The red external fixation light on the headrest was used to illuminate the lower lid margin. Based on the alignment of the arrow, the image of the anterior segment was seen directly on the examination screen. The arrow that appeared in the screen was then changed from the horizontal position to vertical position. The scans were taken 2 seconds after a blink. After the scanning was performed, the software automatically measured and reduced scans to a single image. If the images obtained after scanning were not of satisfactory nature because of eye movement, the scan was repeated.
The lower tear meniscus and conjunctiva were evaluated in central, temporal, and nasal segments of each eye with a digital caliper. Prior to the measurements of tear meniscus and conjunctivochalasis areas, these images were digitally magnified 3 times to improve accuracy of defining borders of the tear meniscus and adjacent structures including conjunctiva, lower lid, and cornea ( Figure 1 ). A tear meniscus was defined as the triangular-shaped wedge of tear film between the lower lid margin and ocular surface (cornea/conjunctiva) ( Figure 1 ).
The method used to measure the cross-sectional area in images taken by the RTVue-100 is provided in Figure 2 . To measure the cross-sectional area of conjunctivochalasis, the images were digitally magnified, tissue landmarks were identified by differences in brightness between tissues, and visual clues such as spaces under the conjunctiva were used to identify the starting point of prolapsing. After evaluating these landmarks, 2 lines were placed pointing to the intersection of the inferior cornea/bulbar conjunctiva and lower lid margin. Finally, the surface of the prolapsed conjunctiva was outlined with the software and the area of the conjunctiva protruding into the angle formed by these 2 lines was measured in mm 2 using the instrument’s software. The distance between points on the peripheral cornea and lower lid margin was measured before and after treatment in 4 patients with central conjunctivochalasis.
In order to evaluate inter- and intraobserver variability, measurements were initially made twice by the first examiner (K.G.) at different times. Next, a second examiner (C.H.), previously informed about the nature of the study, took the same measurements from the same images obtained, with no knowledge of the first examiner’s measurements. Finally, the mean of the repeated measurements taken by the first examiner was used for statistical analysis.
The data were analyzed using SPSS 15.0 for Windows (SPSS Inc, Chicago, Illinois, USA). Intraclass correlation coefficients and Cronbach’s alpha coefficients were calculated for the intraindividual and intraobserver variation. The intraclass correlation coefficient is commonly used as a measure of reliability, with a value of 1 representing a perfect correlation. To compare the baseline and follow-up measurements, paired-samples t test was used. For correlations, Spearman rank correlation coefficient was used. A value of P ≤ .05 was considered to be statistically significant.
The mean age of patients was 69.0 years, with a range of 56 to 87. There were no postoperative complications during the follow-up period. At the first month postoperatively, all patients reported improvement in irritation symptoms. The inferior tear meniscus, visualized after fluorescein staining that was noted to be interrupted by chalasis preoperatively, was found to be continuous in all patients postoperatively.
Intraobserver and Interobserver Variability
Repeated measurements of cross-sectional tear meniscus and conjunctivochalasis areas obtained by the first examiner were analyzed and no statistically significant difference was found between these 2 different measurements (all P values > .05). Intraclass correlation coefficient values for intraobserver and interobserver agreement between the baseline and follow-up measurements of cross-sectional tear meniscus and conjunctivochalasis areas are provided in the Table . The correlation coefficients ranged from 0.938 to 0.976, indicating good agreement between measurements made by the 2 examiners. Intraobserver and interobserver correlation plots are provided in Figures 3 and 4 .
|Variables||Intraobserver/Intraclass Correlation Coefficient (95% CI)|
|Before (n = 36)||After (n = 36)|
|TMA (mm 2 )||0.998 (0.995–0.999)||0.999 (0.998–1.000)|
|CChA (mm 2 )||0.998 (0.996–0.999)||0.994 (0.988–0.997)|
|Variables||Interobserver/Cronbach’s Alpha Coefficient (95% CI)|
|Before (n = 36)||After (n = 36)|
|TMA (mm 2 )||0.993 (0.971–0.992)||0.997 (0.988–0.997)|
|CChA (mm 2 )||0.987 (0.974–0.993)||0.988 (0.977–0.994)|