Histopathologic findings after Nd:YAG transscleral cyclophotocoagulation

Histologic Changes Following Continuous Wave and Micropulse Transscleral Cyclophotocoagulation: A Randomized Comparative Study

Purpose

To compare the macroscopic and microscopic histologic changes in eyes treated with micropulse transscleral cyclophotocoagulation (MP-TCP) versus continuous wave transscleral cyclophotocoagulation (CW-TCP).

Methods

Twelve halves of globes from three pairs of adult cadaveric eyes were randomly assigned to nontreated control, CW-TCP, single MP-TCP treatment, or double MP-TCP treatments, and then sectioned for histologic analysis. Presence or absence of the following four unique histologic changes was recorded: splitting within the ciliary process epithelium (splitting), separation of the pigmented ciliary process epithelium from the stroma (separation), coagulation of collagen and destruction of ciliary process stroma (coagulation), and full-thickness destruction of ciliary process epithelium (destruction).

Results

A total of 498 slides were analyzed, and laser scars in all treated specimens were located in the pars plana. Logistic regression analysis showed that compared with controls, CW-TCP-treated specimens were significantly more likely to experience separation (odds ratio [OR] = 11.1, P = 0.02), coagulation (OR = 24.3, P = 0.002), and destruction (OR = 11.1, P = 0.03). Destruction of the ciliary process epithelium was observed exclusively in CW-TCP-treated sections. No significant differences in histologic features were observed between controls and MP-TCP.

Conclusions

MP-TCP does not produce significant histologic changes in cadaveric eyes, whereas CW-TCP treatment does.

Translational Relevance

These findings improve understanding of the mechanism of MP-TCP, help explain the increased rates of adverse effects following CW-TCP treatment compared with MP-TCP, and describe effects of MP-TCP at various doses.

Pathology of cyclodiode laser: a series of nine enucleated eyes

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.

Ciliary body ablation: where are we and how did we get here?

Management of intraocular pressure remains the cornerstone of glaucoma treatment. Related medical and surgical practices involve increasing aqueous outflow or decreasing aqueous production. Filtration procedures that increase aqueous outflow are the first-line surgical defense in glaucoma. However, some cases of glaucoma are resistant to such treatment. In these cases, ciliary body ablation by various methods has had substantial success. Surgical manipulation of aqueous production has been used in glaucoma management since the turn of the century. Techniques have progressed markedly as technology has produced more discrete therapies designed to decrease aqueous production by destroying ciliary body epithelium. Over the past 90 years success has been achieved with a wide range of techniques, from surgical disinsertion of the ciliary body to recent laser and ultrasound techniques. With the development of more precise contact lasers and endoscopic visualization, side effects have been reduced and clinical success rates increased.

Ultrasound biomicroscopic imaging of the effects of YAG laser cycloablation in postmortem eyes and living patients

PURPOSE

The authors performed a series of experiments designed to determine if early effects of YAG laser cycloablation could be detected by ultrasound biomicroscopy in postmortem eyes and living patients. They also designed an apparatus that allowed simultaneous ultrasound biomicroscopic imaging of YAG laser cycloablation.

METHODS

Treated and untreated regions of postmortem eyes treated with YAG cycloablation were imaged and compared. Treatment was placed at varying distances from the limbus in postmortem eyes and the resulting effects imaged. Histologic examinations were performed after imaging. Six living patients had ultrasound biomicroscopy before and after YAG cycloablation. An apparatus combining contact YAG laser and ultrasound biomicroscopy was used in postmortem eyes.

RESULTS

Early treatment effects imaged included ciliary epithelial disruption, ciliary epithelial separation, and bubble formation. Ultrasound biomicroscopic findings varied with the distance of treatment from the limbus and were maximal below the treatment site. Results of histologic examination showed close correlation to the ultrasound biomicroscopic images. Similar findings to those found in postmortem eyes were found in living patients after treatment. The apparatus combining contact YAG and ultrasound biomicroscopy allowed realtime imaging of effects of YAG laser cycloablation.

CONCLUSIONS

The ability of ultrasound biomicroscopy to detect changes associated with cyclodestructive procedures potentially could provide us with a method of improving treatment precision and correlating treatment effect with clinical response.

A clinicopathologic correlative study of noncontact transscleral Nd:YAG cyclophotocoagulation

We studied the histopathologic changes of three eyes enucleated two weeks, eight weeks, and 17 months, respectively, after noncontact Nd:YAG cyclophotocoagulation. The histologic findings at two weeks were destruction of the nonpigmented and pigmented ciliary body epithelium, occlusion of the capillaries of the ciliary processes, and ciliary body stromal necrosis in the region of the processes. Hyperplasia of the pigmented and nonpigmented epithelium, fibrosis and near total atrophy of the ciliary processes, and partial atrophy of the ciliary muscles were present at eight weeks and 17 months. We concluded that application of treatment 1.0 to 1.5 mm posterior to the corneoscleral limbus selectively destroys the pars plicata, and that, histologically, the mechanism for reducing intraocular pressure appears to be destruction of ciliary processes with reduction of aqueous formation.

High incidence of sympathetic ophthalmia after contact and noncontact neodymium:YAG cyclotherapy

BACKGROUND

Two cases of sympathetic ophthalmia occurring after noncontact neodymium:YAG (Nd:YAG) cyclotherapy have previously been reported. In each case, the patient had undergone filtering surgery in the exciting eye. Although in each case Nd:YAG cyclotherapy was the last surgery performed, the inciting event of sympathetic ophthalmia was unclear.

METHODS

The authors studied three additional patients who developed sympathetic ophthalmia after Nd:YAG cyclotherapy for glaucoma.

RESULTS

Two patients developed sympathetic ophthalmia 4 months after noncontact Nd:YAG cyclotherapy, and 1 patient developed sympathetic ophthalmia 18 months after contact Nd:YAG cyclotherapy. All patients had previous cataract extractions but no filtering surgery in the exciting eye. Clinical features included chronic iridocyclitis, choroidal folds, Dalen-Fuchs nodules, and optic disc edema. Combining these cases with the two previously reported cases, the incidence of sympathetic ophthalmia at our institution thus far is 5.8% (4 of 69) and 0.67% (1 of 150) after noncontact and contact Nd:YAG cyclotherapy, respectively.

CONCLUSIONS

The incidence of sympathetic ophthalmia after Nd:YAG cyclotherapy is high compared with other ocular procedures. The clinician should vigilantly monitor patients after Nd:YAG cyclotherapy and report additional cases that may have occurred at other institutions.

Laser placement in noncontact Nd:YAG cyclophotocoagulation

We treated 40 eyes of 40 patients by using noncontact transscleral Nd:YAG cyclophotocoagulation to determine whether treatment 1.5 or 3.0 mm posterior to the corneoscleral lumbus was preferable. Patients were randomly assigned to one of the treatment groups, and all other variables, including power, number, and distribution of laser applications, were kept constant. Six months postoperatively, those treated 1.5 mm posterior to the corneoscleral limbus had a lower intraocular pressure (P = .0047) than those treated 3.0 mm from the corneoscleral limbus. The 1.5-mm group also required fewer retreatment (P = .017) and had a slightly lower occurrence of visual acuity loss after this procedure. We believe it may be advantageous to locate the laser application approximately 1.5 mm posterior to the corneoscleral limbus, rather than further posteriorly, when performing noncontact transscleral Nd:YAG cyclophotocoagulation.