Pathology of cyclodiode laser: a series of nine enucleated eyes

Abstract

Aim: To study the histological effects of cyclodiode laser treatment in humans, and to compare these findings with the clinical course, treatment response, complications, and indications for enucleation.

Method: Detailed histological examination of nine enucleation specimens was undertaken in conjunction with a retrospective review of patient case notes.

Results: Retreatments had been undertaken in three cases. Although all globes showed damage to pars plicata, intact ciliary processes within the treatment zone were present in all cases. Pars plana injury was also noted in two thirds of cases. Inflammation was mild. Ciliary epithelial proliferation was seen in most cases with increasing time following treatment, in a disorganised pattern, without replication of the ciliary epithelial bilayer. No regeneration of the ciliary processes with fibrovascular cores was found. The three patients with good IOP control at enucleation had all had multiple diode treatments. Neither phthisis nor sympathetic ophthalmia was seen.

Conclusions: Diode laser cyclophotocoagulation produces very characteristic injury to pars plicata, which frequently extends into pars plana, but with only mild persisting inflammation. Ciliary processes are, however, frequently spared within the treatment zone and may account for early or late treatment failure.

Figure 1

(A) Low power photomicrograph of pars plicata showing severe, total destruction of ciliary processes with pigment clumping, loss of vessels, and little epithelial regeneration in case 5, 7 months after diode treatment. Haematoxylin and eosin. Original magnification ×40. (B) Low power photomicrograph of pars plicata showing damaged central zone with sparing of anterior and posterior processes (arrows) in case 5, 7 months after diode treatment. Haematoxylin and eosin. Original magnification ×40. (C) Medium power photomicrograph of haphazardly regenerated non-pigmented epithelium (arrows) over damaged pars plicata with underlying pigment clumping in case 3, 12 months after diode treatment. Haematoxylin and eosin. Original magnification ×100.

Figure 2

Low or medium power photomicrograph of severely damaged pars plana with no residual or regenerated epithelium and pigment clumping in case 2, 5 months after diode. Haematoxylin and eosin. Original magnification ×40.

Figure 3

Medium power photomicrograph of damaged iris base with no residual pigment epithelium, necrosis of stroma and vessels, adjacent to severe injury to pars plicata, in case 5, 7 months after diode. Haematoxylin and eosin. Original magnification ×100.

Figure 4

Low power photomicrograph of scarred sclera (between arrowheads) with increased density of fibroblasts and new vessels overlying severely damaged pars plicata with total destruction of ciliary processes and pigment clumping in case 6, 4 months after diode treatment. Haematoxylin and eosin. Original magnification ×40.