Sir,

Transpupillary thermotherapy (TTT) has been successfully used for treatment of subfoveal choroidal neovascularisation (CNV).1 Safety however remains a concern, given its narrow therapeutic window.2 We report a haemorrhagic retinal detachment (HRD) complicating TTT for CNV.

Case report

A 75-year-old diabetic, hypertensive, and cardiac man complained of poor vision OD for 2 months. Best-corrected visual acuity was 6/18 OD, and 6/6 OS. Anterior segment OU was unremarkable except bilateral pseudophakia. Fundus examination OD showed a large CNV with serous macular detachment and subretinal haemorrhage (Figure 1a). There was no evidence of age-related macular degeneration (AMD), or polypoidal choroidal vasculopathy (PCV). The left fundus was normal. Fundus fluorescein angiogram OD showed a predominantly occult CNV (Figure 1b). Indocyanine-green angiography ruled out PCV.

Figure 1
figure 1

(a) Fundus photograph OD showing a large area of choroidal neovascularisation (CNV) with serous macular detachment, and subretinal haemorrhage temporally. (b) Late-phase fluorescein angiogram reveals hyperfluorescence from the occult submacular CNV with a small temporal classic component; and blocked fluorescence temporally due to subretinal haemorrhage. (c) At 10 days after transpupillary thermotherapy (TTT), an extensive haemorrhagic retinal detachment was noticed, involving the posterior pole and temporal midperiphery, with organised subretinal blood temporal to fovea, and preretinal haemorrhage. (d) B-scan ultrasonography, 6 weeks after the complication, showing breakthrough vitreous haemorrhage with reduced height of the haemorrhagic detachment.

The options of observation, PDT or TTT were offered. With patient's informed consent and approval of the institutional review board, TTT was performed with a slit-lamp mounted 810-nm diode laser. Threshold power was determined with an inferonasal test spot. The lesion was treated with five 500–600 mW spots, each 3 mm, lasting 1 min. Power was reduced by 10% over the haemorrhage; increased similarly over serous detachment. No retinal blanching occurred.

The patient's vision suddenly dropped to hand motions 10 days post-TTT. Fundus examination revealed a massive posterior HRD (Figure 1c). Haematological investigations, cardiac, and carotid status were normal; he was not on anticoagulants. B-scan ultrasonography confirmed clinical findings; there was no suprachoroidal haemorrhage. Afterc 6 weeks, vision remained poor; fundus was not visible. Ultrasound revealed breakthrough vitreous haemorrhage, with reduced height of HRD (Figure 1d). The patient did not follow-up subsequently. When contacted a year later, he reported no change in visual status.

Comment

AMD-related CNV may rarely bleed spontaneously at the stage of disciform scar, predisposed by systemic anticoagulants, hypertension, and cardiovascular disease.3 Idiopathic CNV has a better prognosis; but older patients and larger lesions fare worse, irrespective of the baseline acuity.4 In our patient, HRD was probably caused by TTT-induced vasodilatation, and subsequent closure,2 resulting in dehiscence of choroidal vessels, weakened by age, hypertension, atherosclerosis, and diabetes. The use of multiple burns might also have contributed to HRD, by excessive thermal damage at the overlapping edges. However, we did not observe any visible retinal whitening, popping sound, or patient discomfort during or after TTT. Most patients with occult CNV have lesions larger than two disc areas,5 and therefore require either multiple spots;6 or large-spot TTT.7, 8 There is no evidence in the literature of the superiority of one technique over the other. Similar to multiple spots, a large spot is also likely to deliver excess power by increased uptake in areas with subretinal blood/pigment, which we could avoid by titrating the power of individual burns.

We report a hitherto-undescribed complication of TTT. The older patients undergoing TTT for idiopathic CNV should be cautioned about the small risk of severe visual loss, especially when pretreatment acuity is good, and CNV is extensive.