Sir,

We report a patient with thyroid eye disease (TED) in whom corneal striae were a sign of increased orbital pressure.

Case report

A 48-year-old Oriental lady with TED was referred urgently to the orbital clinic. She had had previous radioactive iodine treatment and was euthyroid. She was a smoker.

Although her best-corrected visual acuities were 6/12 bilaterally, examination of the anterior segments revealed bilateral corneal stromal vertical striae (Figure 1a and b) and shallow anterior chambers. Hertel exophthalmometry was 21 mm bilaterally. Ishihara colour vision and visual fields to confrontation were normal.

Figure 1
figure 1

Corneal striae in both left (a) and right eye (b).

Full size image

Gonioscopy confirmed the angle grade as 0-I in all quadrants using Schaffer's method. Her intraocular pressures (IOPs) in primary position were right 22 mm Hg and left 25 mmHg with further increase in upgaze (right 28, left 31 mmHg). She was started on topical latanoprost to both eyes.

A few months before her referral she had undergone bilateral 11/2 wall endoscopic orbital decompression for bilateral optic nerve compression. The corneal striae had also been noted at that point.

Orbital computed topography was performed revealing adequate bony decompression but increased rectus muscle bulk on both sides. In view of increased muscle bulk and risk of further compressive optic neuropathy from increased orbital pressure (as evidenced by anterior segment findings), she underwent a three-wall external orbital decompression followed by orbital radiotherapy (20 G in 12 fractions).

After her surgery, visual acuities were 6/9 (pinhole 6/6) bilaterally and anterior segment examination revealed minimal corneal punctate epitheliopathy with reversal of all corneal striae. The anterior chamber also deepened (grade II–III in all quadrants). The IOPs were controlled on topical latanoprost (right 18, left 18) and dilated fundoscopy confirmed normal discs and retina. There was no change in her refraction at any point.

Comment

Corneal disease in TED has been described in the context of tear film instability, lagophthalmos, exposure keratitis, and corneal astigmatism. 1

The Oriental upper eyelid has subcutaneous, suborbicularis, and pretarsal fat components. The orbital septum is tighter compared to the Caucasian orbits with the orbital septum fusing with the levator aponeurosis below the superior tarsal border.2

Our patient had enlarged extraocular muscles, mild proptosis, a tight orbital septum and we feel that the resultant high orbital pressure induced globe compression. In the presence of a tight orbital septum, the increased orbital pressure may manifest as corneal striae.

Striae results from the whole cornea swelling and buckling back upon itself causing vertical folds or lines in the Descemet's membrane.3 In this case the corneal changes reversed with further orbital decompression, which opened the septum and enlarged the orbital bony cavity thus reducing the orbital pressure. Clinicians should be aware of this sign in TED as an indicator of a tense orbit in the absence of marked proptosis.