An unusual case of inflammatory Terrien’s marginal degeneration with pseudo pterygium

Terrien’s marginal degeneration (TMD) is a rare form of slow-progressing, bilateral, but asymmetric degeneration of peripheral cornea characterized by peripheral stromal thinning, neovascularization, lipid deposition, and sometimes opacification of cornea. Although TMD is mostly considered a noninflammatory disease with superior peripheral corneal involvement, a variant form characterized by prominent inflammation and inferior corneal involvement exists.[1] Case Report A 40-year-old male patient, presented to the clinic with a progressive diminution of vision in both eyes and the growth of a fleshy mass in the left eye for the past 10 years. He also gives a history of occasional episodes of red, irritated, photophobic, painful eyes for the past 11 years. The patient was found to have an uncorrected visual acuity of 6/24 in the right eye and 5/60 in the left eye. With + 1.00 Diopter sphere/−6.00 diopter cylinder × 65°, the visual acuity improved to 6/12 in OD and there was no improvement in OS. His keratometric values (Bausch and Lomb) in OD were K1 = 41.25 D and K2 = 54.50 D, and his mires were very distorted in OS. The patient underwent a thorough slit lamp examination which revealed an inferior circumlinear corneal thinning with intact epithelium, neovascularization, lipid deposition, and intrastromal cyst in OD. The extent of thinning was seen between the 3 o’clock to 10 o’clock position and localized ectasia along the course of the furrow, as shown in Figure 1a. OS showed an “atypical pterygium” grown obliquely onto the cornea, instead of involving the 3 and 9 o’clock meridian with a broad, flat, and leading edge, as shown in Figure 1b. The intraocular pressure and fundus were within normal limits. Corneal topography shows “against the rule” astigmatism in OD and flattening of the cornea in the meridian of pseudopterygium in OS.Figure 1: (a) Slit-lamp image of the right eye showing corneal stromal thinning between 3 o’clock to 10 o’clock and localized ectasia along the course of the furrow. (b) A slit-lamp image of the left eye shows pseudopterygium grown obliquely on the corneaA complete blood profile and rheumatologic investigations were done which were negative. He was diagnosed with a case of both eyes inferior inflammatory TMD with OS pseudopterygium. He was explained about the progressive nature of the disease and the need for regular follow-up was emphasized. The patient was also explained to avoid any inadvertent trauma to his eyes. In the left eye, the patient was treated with an antibiotic–steroid combination in a tapering dosage to which the patient responded well, and a scleral contact lens was recommended for the right eye. The patient has been explained about the need for full thickness or lamellar keratoplasty in the future, but the patient is not willing to any surgical intervention at present. Hence, the patient is being managed medically and is kept on regular follow-up for the last 6 months. Discussion TMD is a rare corneal condition. The disease is usually bilateral, but it may progress asymmetrically between the eyes.[2] A study conducted by Chan et al. confirms that TMD emerges at any age, but, on average, manifests after the age of 40 years and affects men more than women.[3] TMD tends to start in the superior nasal quadrant with fine yellow-white punctate stromal opacities that gradually expand and involve the entire circumference of the peripheral cornea with neovascularization, scarring, and lipid infiltration at the leading edge.[4] However, in our case, the disease has started inferiorly with a history of regularly occurring attacks of red eyes with photophobia for more than a decade. As the irritation and redness used to resolve in one eye, a similar attack occurred in the left eye. There was no epithelial loss and no evidence of scleritis in both the eyes. A complete blood profile and rheumatological investigations were done, and the results were negative for PUK. The disease process is extremely slow and may take many years to develop.[5] Furthermore, the inflammatory nature of the disease is rare and the patient lacks signs and symptoms of inflammation, but in our case, there is an inflammatory course of the disease, and other investigators have also discovered a variant of the illness with noticeable inflammatory signs.[6] Hence, it is important to distinguish inflammatory TMD from autoimmune or infectious peripheral ulcerative keratitis. Mooren’s ulcer characteristically has epithelial loss with fluorescein staining at its central edge with central progression, whereas TMD does not show fluorescein staining at its central edge and does not progress centrally. Pseudopterygium is seen in 20% of the cases of TMD.[7] This “atypical pterygium” grows obliquely onto the cornea instead of involving the 3 and 9 o’clock meridian, and has a broad, flat, leading edge. Pseudopterygium is a conjunctival adhesion to the peripheral cornea, secondary to corneal limbus damage, and it may occur at any location. Diagnosis of this atypical pterygium is important to prevent corneal perforation that may arise on its excision. All patients should be informed about the possibility of trauma-related and spontaneous perforations to emphasize the requirement of wearing protective eyewear. Conclusion Routine follow-up of TMD cases is important to know the trend of the disease, and its precipitating factors, as spontaneous perforation may take place, and it is also important to recognize the pseudopterygium, as its removal may lead to corneal perforation. Rigid contact lenses or glasses can be used to treat severe astigmatism. An option of full thickness or lamellar keratoplasty has to be kept in mind in case of an impending perforation. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.