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Editor,—Early surgical intervention has been reported to achieve closure of laser induced macular holes.1 2 We report a case of spontaneous closure of a laser induced macular hole indicating that surgery should not be undertaken before a reasonable period of observation.
A 24 year old physics postgraduate student accidentally sustained an injury to his right eye while aligning an 806 nm titanium-sapphire laser. The laser parameters were pulse energy 2 mJ, pulse duration 100 femtoseconds, and repetition rate 10 Hz. The duration of exposure was limited by his blink reflex. He noted immediate impairment of central vision in this eye.
When examined by an ophthalmologist 2 days later, visual acuity was 6/18 in the right eye. Amsler testing demonstrated an absolute paracentral scotoma which was 1.5° in diameter and abutted fixation. A full thickness macular hole was present with loss of both neurosensory retina and retinal pigment epithelium (RPE). The hole was approximately 150 μm in diameter and located at the temporal margin of the foveola. There was no associated retinal oedema or haemorrhage. Fluorescein angiography showed a hyperfluorescent transmission defect.
At 4 weeks after injury, a cuff of subretinal fluid had developed around the macular hole (Fig 1). Visual acuity remained 6/18, but the size of the scotoma had correspondingly increased. The option of surgical intervention was considered, but a conservative approach was chosen at this stage.
The patient noticed a gradual improvement in his vision approximately 4 weeks later. At 12 weeks after injury, his visual acuity was 6/6. Amsler testing now demonstrated a relative paracentral scotoma which was 0.5° in diameter and located 1° from fixation. The macular hole was closed with residual RPE depigmentation at the site of the laser injury (Fig 2). There was no posterior vitreous detachment. No further changes occurred during 6 months of follow up.
The mechanism of macular hole formation following accidental exposure to a Q switched laser is photomechanical tissue disruption (rather than photocoagulation).3 The natural history of these laser induced macular holes remains uncertain because this type of injury is uncommon. In a series of five cases, spontaneous closure was only observed in one eye which occurred at 3 weeks after injury.4 Two other cases of non-resolving laser induced macular holes have also been reported.5 6
This case report confirms that laser induced macular holes can close spontaneously with visual improvement. Furthermore, this event may be delayed for 8–12 weeks following the injury. The occurrence of spontaneous closure could possibly be influenced by macular hole size. The diameter of macular holes that have spontaneously resolved was 150 μm in this case and 180 μm in the previous report.4While non-resolving macular holes have generally been larger (250–500 μm in diameter4-6), a 75 μm macular hole has been observed to enlarge without spontaneous closure.4Spontaneous closure of small traumatic macular holes (0.1 disc diameter) has also been reported at 3–4 months after the injury.7
There have been two recent reports of laser induced macular holes being successfully treated by early surgical intervention, performed at 3 weeks1 and 6 weeks2 after injury, respectively. In both cases, the macular hole was 300 μm in diameter. Surgery comprised pars plana vitrectomy, removal of the posterior cortical vitreous, and gas tamponade followed by face down posturing. Additional procedures comprised stripping of an early epiretinal membrane1 and adjuvant therapy with autologous thrombocyte concentrate.2 The rationale for surgical treatment was relief of tangential traction on the edges of the hole and reattachment of the retina by gas tamponade, as for idiopathic macular holes.8
It is, however, important to recognise that laser induced macular holes can resolve spontaneously. Internal limiting membrane changes induced by laser injuries are capable of spontaneous regression, as demonstrated by reports of significant macular pucker improving spontaneously.6 9 Reparative events within the neurosensory retina and RPE may also influence macular hole closure, comprising fibroglial and retinal pigment epithelial hyperplasia.10 Surgical intervention for laser induced macular holes should therefore not be considered before a reasonable period of observation.
Sources of funding: None
Proprietary or financial interests: None