Rare Choristoma of the Tarsal Conjunctiva: Critical Inspection Prevents Unnecessary Mutilation.

We report a case of a 26-year-old male patient with an incidental finding of a flesh-colored tumor with few vellus hairs on its surface, located on the fornix and the tarsal conjunctiva of the left lower eyelid. Histology of the biopsy showed a choristoma consisting of abundant vellus hairs, sebaceous glands, and sparse lacrimal gland tissue. Recognition of conjunctival vellus hairs is significant and raises the suspected diagnosis of choristoma, which can be confirmed by a small sample biopsy. A complete excision is unnecessary and possible surgical complications can be prevented. Choristomas of the tarsal conjunctiva are very rare and, to our knowledge, this is the first histological documentation of a choristoma containing vellus hair located on the tarsal conjunctiva. In addition, we review the histopathological findings of choristomas and their differential diagnoses.

Dependability of posterior-segment spectral domain optical coherence tomography for measuring central corneal thickness.

PURPOSE: The aim of this study was to assess the intersession and interobserver reliability of central corneal thickness (CCT) measurements using a posterior-segment spectral domain optical coherence tomography (SD-OCT). METHODS: Sixty patients were examined with a posterior-segment SD-OCT system (Topcon 3D-OCT). To analyze intersession reproducibility, 1 examiner measured CCT in 60 eyes 2 times 1 week apart, and to study interobserver reproducibility, a second examiner obtained another measurement during the first session. Within-subject reproducibility, coefficient of reproducibility (CR), and intraclass correlation coefficients (ICC) were calculated. Agreement between Topcon 3D OCT and ultrasound pachymetry (USP) was also assessed. RESULTS: Posterior-segment SD-OCT showed an intersession reproducibility of 12.7 µm (CR = 2.4%) and an excellent ICC (0.96). No systematic difference between sessions was found (average difference, 1.7 µm; P = 0.15). We found no significant bias between observers (mean difference, -1.5 µm; P = 0.29). The interobserver reproducibility was 16.4 µm (CR = 3.1%), and the ICC was 0.94. Topcon 3D OCT CCT values were lower than USP readings (mean difference, 7.6 ± 8.1 µm; 95% confidence interval, 9.9-5.3 µm; P < 0.001). CONCLUSIONS: With a commercially available retinal SD-OCT system, reliable intersession and interobserver CCT measurements can be feasibly obtained. The criteria for a significant change, which would be the one exceeding the reproducibility, indicate that intersession and interobserver variations in CCT of more than 13 and 16 µm, respectively, may reflect true corneal change with this particular device. These estimates should help investigators and clinicians differentiate actual CCT modification from measurement random error. The slight CCT underestimation with respect to USP is within the range of other OCT devices.

Precision of high definition spectral-domain optical coherence tomography for measuring central corneal thickness.

PURPOSE: This study was intended to assess the reliability of central corneal thickness (CCT) measurements using Cirrus high-definition optical coherence tomography (HD-OCT) in healthy subjects and its accuracy compared with ultrasonic pachymetry. METHODS: Seventy-seven consecutive subjects were recruited for evaluating repeatability, and agreement between two examiners. To analyze repeatability, one examiner measured 77 eyes four times in succession. To study agreement between two observers, a second independently trained examiner obtained another CCT measurement. We also measured eyes in a subgroup of 20 patients using standard ultrasonic pachymetry. Within-subject standard deviation (S(w)), coefficient of variation (CV), limits of agreement (LoA), and intraclass correlation coefficient (ICC) data were obtained. RESULTS: For repeatability, the S(w) and precision (1.96 × S(w)) were 4.86 and 9.52 µm, respectively. Intraobserver CV was 0.89% and the ICC was 0.98 (95% confidence interval [CI], 0.97-0.99). For agreement between two examiners, the S(w) and precision were 7.58 and 14.85 µm, respectively; the CV was 1.40%. The mean difference between observers was -0.13 µm (95% CI, -1.85 to 1.58; P = 0.87). The width of the LoA was 29.64 µm. Median difference between Cirrus HD-OCT and ultrasound CCT measurements was -4.5 µm (interquartile range, -7.0-0.0; P = 0.04). CONCLUSIONS: Cirrus HD-OCT provides repeatable CCT measurements, good agreement between two independently trained examiners, and its systematic bias compared to ultrasonic pachymetry is clinically negligible. Therefore, research laboratories and eye clinics using Cirrus HD-OCT as a diagnostic imaging method, can also benefit from a reliable noncontact pachymeter when counseling patients with glaucoma and those undergoing corneal and refractive surgeries.