Abstract
Purpose
to report the utility of Anterior Segment Optical Coherence Tomography (AS OCT) for planning superficial sclerectomy in a patient with nevus of Ota.
Observations
Oculodermal melanocytosis, also called nevus of Ota, is a benign pigmentary disorder that involves the skin innervated by the first and second branches of the trigeminal nerve. To reduce these black or brownish lesions, different surgical treatments have been reported, such as flipped scleral flap, sclera allograft and the grabbing method. Superficial sclerectomy is a recent technique that has proven effective in improving scleral pigmentation. Although this procedure allows the operating time to be reduced and results in a smoother scleral bed surface, it has a limitation, represented by the difficulty of estimating the depth of the sclerectomy: an inaccurate estimate or incorrect depth could cause an inadequate deep scleral dissection with excessive weakening of the sclera. We report a case of a 27-year-old patient with nevus of Ota undergoing superficial sclerectomy. The depth of scleral pigmentation was evaluated with AS OCT images before the surgery, allowing a superficial sclerectomy to be performed with a precalibrated diamond blade.
Conclusions and Importance
In oculodermal melanocytosis (nevus of Ota) the use of AS OCT images showing the depth of scleral pigmentation could lead to the most effective and safest surgical choice for each case.
1
Introduction
Oculodermal melanocytosis is a brownish, blue gray or black pigmentation of the eye and periorbital skin along the distribution of the ophthalmic and maxillary branches of the trigeminal nerve. , The pathology was first described in the mid 1800s in reference to a patient with cutaneous hyperpigmentation and melanoma of the sclera. The condition is also called nevus of Ota, since Ota described the ocular pigmentation in the 1939. The nevus can be unilateral (95%) or bilateral (5%) and, in addition to the skin, it can involve the ipsilateral episclera and sclera, conjunctiva, choroid and even the optic nerve. Oculodermal melanocytosis occurs more frequently in women and Asians, with an incidence of 0.2–1%. The etiology is not completely known, but it is probably related to an incomplete melanocyte migration from the neural crest to the epidermis during the embryonic stage. Numerous patients with oculodermal melanocytosis suffer because of their condition and this is reflected in personal relationships. Several methods have been used to reduce these black or brownish lesions, including flipped scleral flap, sclera allograft and the grabbing method. Some authors have shown good results with superficial sclerectomy : the main problem in this case is knowing how much scleral tissue should be removed to eliminate the pigmented area without weakening the sclera. We report the utility of Anterior Segment Optical Coherence Tomography (AS OCT) in the preoperative planning of superficial sclerectomy in a patient with nevus of Ota. The preoperative depth of scleral involvement was evaluated with AS OCT images with a measurement of scleral melanocytosis depth in order to quantify the size of the sclerectomy.
2
Case report
We report a case of 27-year-old Caucasian man with a right congenital periocular hyperpigmentation with cutaneous and scleral involvement ( Figs. 1 and 2 ). The patient came to us expressing a desire to remove the scleral pigmentation, as it caused him great discomfort in social relations. During the examination, we realized how much the physical problem created distress for him in his interpersonal relationships. He avoided direct eye contact during conversations and feared social interactions. The patient reported that this discomfort had created a qualitative impairment of his social life that required the intervention of a psychotherapist. Therefore, we considered a superficial sclerectomy to improve this emotional wellbeing, believing that this would have positive repercussions on the patient’s quality of life and self-confidence.
The pros and cons of treatment, such as an improvement in scleral pigmentation versus a risk of perforation, neuropathy, infections, scleropathy and scleral weakening, were discussed with the patient who expressed his willingness to undergo the surgery. The study was conducted in accordance with the tenets of the World Medical Association’s Declaration of Helsinki and informed consent for the surgical reduction of ocular pigmentation was obtained from the patient.
The patient had preoperative and postoperative assessments, including refraction with best corrected visual acuity (BCVA), intraocular pressure (IOP), slit lamp examination and fundus examination. BCVA was 20/20 and IOP was normal in both eyes. On slit lamp examination there were no abnormalities in the cornea, anterior chamber or crystalline lens except the sclera hyperpigmentation. The fundus finding was normal. Scleral pigmentation was more marked in inferior temporal and inferior nasal sectors as well as in the superior one, but we decided not to treat this quadrant because it was hidden by the upper eyelid ( Figs. 1 and 2 ).
In order to plan the surgical sclerectomy we investigated the scleral pigmentation with the Spectralis Anterior Segment Module (Spectralis HRA OCT 2 MC; Anterior Segment Module, Heidelberg Engineering GmbH, Heidelberg, Germany). The Spectralis Anterior Segment Module enables high resolution OCT imaging of the cornea, sclera, and anterior chamber angles. The acquisition speed is 80,000 A scans per second. We used 15 × 10° scans (8.3 mm × 5.6 mm) for a total of 161 B scans spaced at 35 μm; each scan has an axial resolution of 3.9 μm/pixel and a side resolution of 5.7 μm/pixel. This technology seems appropriate for the study of scleral tissue, as it allows us to evaluate the pigment depth and the amount of scleral involvement. The OCT scans showed the presence of pigmented areas in the sclera, with a greater density in the superficial than in the deep sclera, as well as a different reflectivity between the superficial and deep sclera, marked by a separation line. The depth of the superficial scleral pigmentation was measured with AS OCT, which enabled us to plan the depth of the sclerectomy ( Fig. 3 A–B).
Since the upper and lower eyelids covered the superior and inferior portions of the sclera, we limited the reduction of ocular pigmentation to the inferior and inferior temporal areas.
After the application of topical and peribulbar anesthesia, the conjunctiva and Tenon capsule on the temporal and nasal sides of the eye were incised and dissected using Vannas scissors. A two-step surgical approach was used. The first step involved the inferior nasal area of the sclera. Based on the information provided by AS OCT, we were able to plan a 200 μm scleral incision with a precalibrated diamond blade and perform a superficial sclerectomy of 200 μm ( Fig. 4 ). The second step involved the inferior temporal quadrant of the sclera, which we operated one month after the first surgery. In this area, the AS OCT images showed a pigmentation reaching over 250 μm in depth. We performed a sclerectomy of 250 μm and we noticed a lower pigmentation in the deeper part of the scleral flap compared to the superficial area. For this reason, we decided to perform a flipped scleral flap surgery ( Fig. 5 ): after the free scleral flap was dissected, it was flipped over and attached to the scleral bed with 7/0 Vicryl interrupted sutures. This procedure hides the episcleral pigmentation internally, resulting in a less pigmented surface and avoiding excessive weakening of the sclera. Conjunctival peritomy was approximated and sutured using 7/0 Vicryl. Topical 0.3% ofloxacin and 0.1% fluorometholone were used for approximately 2 months postoperatively.
