Efficacy of transpupillary thermotherapy (TTT) in the treatment of occult subfoveal choroidal neovascularization in age-related macular degeneration

Age-related macular degeneration revisited--piecing the puzzle: the LXIX Edward Jackson memorial lecture

PURPOSE

To present the current understanding of age-related macular degeneration (AMD) pathogenesis, based on clinical evidence, epidemiologic data, histopathologic examination, and genetic data; to provide an update on current and emerging therapies; and to propose an integrated model of the pathogenesis of AMD.

DESIGN

Review of published clinical and experimental studies.

METHODS

Analysis and synthesis of clinical and experimental data.

RESULTS

We are closer to a complete understanding of the pathogenesis of AMD, having progressed from clinical observations to epidemiologic observations and clinical pathologic correlation. More recently, modern genetic and genomic studies have facilitated the exploration of molecular pathways. It seems that AMD is a complex disease that results from the interaction of genetic susceptibility with aging and environmental factors. Disease progression also seems to be driven by a combination of genetic and environmental factors.

CONCLUSIONS

Therapies based on pathophysiologic features have changed the paradigm for treating neovascular AMD. With improved understanding of the underlying genetic susceptibility, we can identify targets to halt early disease and to prevent progression and vision loss.

Long-term safety, high-resolution imaging, and tissue temperature modeling of subvisible diode micropulse photocoagulation for retinovascular macular edema

PURPOSE

To determine the long-term safety of high-density subvisible diode micropulse photocoagulation (810 nm), compare the clinical findings with computational modeling of tissue hyperthermia and to report results for a subset of eyes treated for diabetic macular edema (ME) documented pre- and postoperatively by spectral-domain optical coherence tomography.

METHOD

All eyes treated for ME from diabetic retinopathy (diabetic ME) and branch retinal vein occlusion between April 2000 and January 2010 were reviewed for subvisible diode micropulse laser-induced retinal damage. Therapeutic outcomes were reviewed for a subgroup treated for diabetic ME with pre- and postoperative spectral-domain optical coherence tomography. Laser-induced retinal thermal effects were modeled computationally using Arrhenius formalism.

RESULTS

A total of 252 eyes (212 diabetic ME, 40 branch retinal vein occlusion) of 181 patients qualified. None of the 168 eyes treated at irradiance <350 W/cm2 and 7 of 84 eyes at ≥ 590 W/cm2 had retinal damage (P = 0.0001) (follow-up 3-120 months, median, 47). Sixty-two eyes of 48 patients treated for diabetic ME with pre- and postoperative spectral-domain optical coherence tomography with median 12 months follow-up had no retinal injury by infrared, red-free, or fundus autofluorescence photos; fluorescein angiography or indocyanine green angiography; or spectral-domain optical coherence tomography. Central foveal thickness (P = 0.04) and maximum macular thickness decreased (P < 0.0001). Modeling of retinal hyperthermia demonstrates that the sublethal clinical regimen corresponds to Arrhenius integral >0.05, while damage is likely to occur if it exceeds 1.

CONCLUSION

Subvisible diode micropulse can effectively treat retinovascular ME without laser-induced retinal damage, consistent with Arrhenius modeling of pulsed hyperthermia.

Today and future of age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in people over 50 in developed countries. Understanding of the pathologic process, genetic mechanisms, and risk factors of this disease has the benefit of seeking newer and more effective treatment options. Current clinical therapy for AMD shows a dramatic change from a decade ago. Anti-VEGF drug therapy is regarded as the more effective treatment for neovascular AMD now, especially combining PDT therapy. In the future, the genetic and biochemical therapies may be the promising treatments for AMD. This paper will focus on the progress of pathology, candidate genes of AMD, risk factors, and the existing drugs or surgical therapies available, in order to present some new directions of care with the prospect of improved vision in many patients suffered from AMD.

Regression of peripapillary choroidal neovascularization after oscillatory transpupillary thermotherapy and anti-VEGF pharmacotherapy

PURPOSE

We prospectively evaluated a new treatment for recalcitrant choroidal neovascularization (CNV) in 4 patients. We used an infrared laser (810 nm) in oscillatory thermotherapy (OTT) mode combined with indocyanine green (ICG) dye, utilizing the beneficial effect of both thermotherapy and photodynamic therapy. We describe preliminary experiences with ICG-assisted OTT (I-OTT) combined with intravitreal bevacizumab/dexamethasone for refractory peripapillary CNV resistant to standard therapy.

METHODS

Clinical examination, funduscopy, fluorescein angiography, and optical coherence tomography were performed at baseline and postoperatively. Infrared laser spot size was approximately one-half the lesion size (oscillation 2-3 Hz). Intravitreal injections of bevacizumab (1.25 mg) and dexamethasone (1000 µg) were done during the same visit.

RESULTS

Mean follow-up was 12.5 months (range 5-17). Mean energy level was 325 mW (range 200-500) in oscillatory mode (2-3 Hz/sec) pre- and post-ICG infusion. Indocyanine green dose was approximately 1 mg/kg (75 mg/patient). All patients had a single treatment. Mean visual acuity improved in 1 patient from 20/60 to 20/30 and remained the same in the other 3 (20/20, 20/40, and 20/400). At final examination, there was no evidence of clinical or angiographic activity of CNV.

CONCLUSIONS

Indocyanine green-assisted OTT has the potential to treat CNV in wet age-related macular degeneration. It may reduce thermal side effects and eliminate or reduce the need for frequent intravitreal treatment. We postulate that I-OTT has a synergistic effect of thermal energy combined with a weak photosensitizer (ICG) applied in an individualized manner, which minimizes thermal damage to retinal and choroidal tissue. Additional anti-vascular endothelial growth factor pharmacotherapy enhances the effect of I-OTT on abnormal new vessels.

New therapies for neovascular age-related macular degeneration: critical appraisal of the current evidence

During the past 20 years, several multicentre clinical trials have investigated different therapies for neovascular age-related macular degeneration (AMD). These landmark studies have provided the scientific community with powerful data regarding the ability of laser photocoagulation, verteporfin therapy, pegaptanib sodium and submacular surgery to treat particular choroidal neovascular lesion types. Accurate interpretation of data from these trials is essential to enable clinicians to make informed decisions about therapeutic interventions. Furthermore, several new treatment options are likely to become available in the next few years and clinicians will have to decide how effective these therapies may be, and how (or if) they should be used in clinical practice. It is therefore timely to review the strengths and weaknesses of the body of evidence for the currently available therapeutic options for patients with choroidal neovascularization due to AMD. Evaluation of the quality of reporting in past clinical trials will also enable critical review of new studies that will be published in the future. This review summarizes the design, reporting and results of key randomized clinical trials, in addition to evaluating the available evidence for new therapies and identifying the important issues that need to be considered when evaluating their efficacy.

Long term results after transpupillary thermotherapy in eyes with occult choroidal neovascularisation associated with age related macular degeneration: a prospective trial

AIM

To evaluate long term results after transpupillary thermotherapy (TTT) in eyes with exudative age related macular degeneration.

METHODS

In a prospective clinical study eyes with occult or predominantly occult choroidal neovascularisation and no pretreatment were scheduled to have a TTT with a power of 630 mW. Visual acuity for far and near distances as well as contrast sensitivity were evaluated 6, 12, and 24 months postoperatively and statistically analysed.

RESULTS

47 eyes fulfilled the inclusion criteria. Overall, 70% of the patients showed an improved (14%) or had unchanged (56%) ETDRS vision after 24 months. Reading vision was stabilised (51%) or better (5%) in 56% of the eyes at this time. However, the increasing number of eyes with severe deterioration resulted in a significant decrease of both parameters over time (p = 0.0002 and p = 0.0003, respectively). Contrast sensitivity could be maintained (70%) or improved (9%) in 79%. Statistical analyses indicated a trend but no significant decrease over time (p = 0.056).

CONCLUSION

Although in the majority of patients far and near distance acuity could be stabilised on average a significant decrease over time after TTT was observed. Statistical comparison of months 12 and 24 showed no further deterioration.

Transpupillary Thermotherapy With Indocyanine Green Dye Enhancement for the Treatment of Occult Subfoveal Choroidal Neovascularization in Age-Related Macular Degeneration

BACKGROUND AND OBJECTIVES

Transpupillary thermotherapy (TTT) with indocyanine green (ICG) dye enhancement (TTT+) and TTT alone were compared for safety and effectiveness as a treatment of occult subfoveal choroidal neovascularization in age-related macular degeneration.

PATIENTS AND METHODS

Twenty-one patients were randomized to receive TTT (12 eyes) or TTT+ (9 eyes) and observed for at least 6 months. ETDRS visual acuity and fluorescein and ICG angiography were obtained every 3 months.

RESULTS

The median initial visual acuity was 20/80 in the TTT group and 20/100 in the TTT+ group. At 6 months, loss of less than 3 lines of visual acuity was present in 7 of 12 eyes (58%) in the TTT group and 5 of 9 eyes (56%) in the TTT+ group. At the final examination, there was no active choroidal neovascularization exudation in 6 of 12 eyes (50%) in the TTT group and 5 of 9 eyes (56%) in the TTT+ group. The median final visual acuity was 20/125 in the TTT group and 20/160 in the TTT+ group. Ocular or systemic complications were not encountered in either group.

CONCLUSION

TTT with ICG dye enhancement was as safe and effective as TTT alone in this study. However, modifications of treatment protocol would be needed to see whether there is any advantage to using ICG dye enhancement.

Retinal function following transpupillary thermotherapy for occult choroidal neovascularization in age-related macular degeneration: a short-term study by focal electroretinography

PURPOSE

To assess short-term changes in macular function after transpupillary thermotherapy (TTT) in patients with occult subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD), using focal electroretinography (FERG).

METHODS

Twenty-five patients with occult subfoveal CNV due to AMD were treated with TTT delivered using an infrared (810 nm) diode laser (spot size 3.0 mm, laser power 400-600 mW, duration 60 seconds). All patients were clinically evaluated before, 1 and 6 weeks after treatment. Snellen visual acuity (VA) was measured at each visit. Fluorescein angiography (FA) was performed at baseline and 6 weeks after TTT. Focal ERGs were recorded in all patients immediately before and 1 week after TTT in response to an 18-degree diameter, 41 Hz flickering spot (630 nm) centred on the fovea, presented on a steady background in Maxwellian view. A subgroup of 12 patients was also re-tested by FERG at 6-weeks post-TTT.

RESULTS

No significant changes in mean FERG amplitude and phase were observed across the different recording sessions before and after TTT. One week after TTT, four patients had significant (> 2 SD from baseline variability) increases in FERG amplitude and/or phase advances, one had a decrease in amplitude and four had phase delays, compared to baseline. The remaining 15 patients had stable FERGs. Six weeks after TTT, four patients had significant increases in FERG amplitude and/or phase advances, four had decreases in amplitude and/or phase delays, and four had stable FERGs, compared to baseline. Improvement in FERG parameters after TTT was always associated with an improvement in VA and a decrease in exudation. Patients with post-TTT FERG deterioration had stable or deteriorated clinical pictures. At either 1 or 6 weeks post-TTT, the FERG amplitude increase was inversely correlated (p < 0.05) with the baseline FERG amplitude and VA.

CONCLUSIONS

Three major conclusions can be drawn: in a short-term follow-up, TTT was not found to be associated with significant changes in macular function; FERG improvement was associated with VA improvement, and the increase in FERG amplitude was greatest in patients with the worst baseline acuity.

Comparison of photodynamic therapy and transpupillary thermotherapy for subfoveal choroidal neovascularization due to age-related macular degeneration

BACKGROUND

The purpose of this study was to compare photodynamic therapy (PDT) against subthreshold transpupillary thermotherapy (TTT) with a diode laser for subfoveal choroidal neovascularization secondary to age-related macular degeneration (AMD).

METHODS

Patients with subfoveal choroidal neovascularization secondary to AMD were offered PDT as an initial intervention. If they declined PDT, then TTT was offered.

RESULTS

We evaluated and followed 115 consecutive patients for an average of 1 year. The primary outcome measure was visual acuity, but the interventions were also compared on the basis of lesion size and angiographically determined lesion activity. Baseline comparisons between the 2 treatment groups showed significant differences in pretreatment visual acuity, lesion size, and lesion composition. Univariate analysis of outcomes demonstrated equivalence between the treatment groups in final lesion size, angiographic activity, and visual acuity. Multivariate analysis also demonstrated equivalence between the treatment groups in final visual acuity while controlling for age, pretreatment visual acuity, and lesion category. Predominantly classic lesions were associated with poorer visual outcomes.

INTERPRETATION

The PDT and TTT groups were equivalent in terms of all outcome parameters evaluated.

Transpupillary thermotherapy for occult subfoveal choroidal neovascularization: a 1-year, prospective randomized pilot study

PURPOSE

To evaluate the 1-year effect of transpupillary thermotherapy (TTT) on occult choroidal neovascularization membranes (CNV).

METHODS

In this prospective, randomized, controlled pilot study of 28 patients with occult or minimally classic (< 10%) neovascularization membranes with a diameter less than 4500 microm, 19 patients were treated with TTT, while nine received sham treatment. Outcome measures were membrane diameter, visual acuity and reading ability.

RESULTS

The median age of patients randomized to TTT was 78 years (range 24 years); that of patients randomized to sham was 79 years (range 9 years). There was no difference regarding membrane diameter at baseline between the two groups; the median membrane diameters were 3400 microm (range 2400 microm) in the TTT group and 3200 microm (range 2300 microm) in the sham group (p = 0.639). Visual acuity (VA) was similar, with a median of 0.2 (minimum-maximum 0.08-0.5) in the TTT group and a median of 0.16 (min-max 0.10-0.32) in the sham group. A total of 21 patients were followed for 1 year, 13 in the TTT group (2.7 treatments/patient) and eight in the sham group. Membrane diameter increased in both groups, by a median of 350 microm (range 1600 microm) in the TTT group and 800 microm (range 1700 microm) in the sham group (p = 0.414), respectively, and there was a loss in VA of > or = 15 letters in 5/13 patients (38%) in the TTT group compared with 2/8 patients (25%) in the sham group (p = 0.266). Reading ability deteriorated equally over time in both groups. Seven patients were lost to follow-up due to reluctance to continue in the study (n = 4) or development of a classical component > 50% (n = 3) requiring photodynamic therapy (PDT).

CONCLUSION

The results from this randomized, prospective pilot study of TTT for occult CNV did not indicate that TTT has a beneficial effect on visual outcome 1 year after treatment compared with the visual outcome that results from the natural course of the disease. The small study size limits statistical power and results from large control studies are needed.

[Transpupillary thermotherapy for occult choroidal neovascularizations]

PURPOSE

This contribution describes the results of transpupillary thermotherapy (TTT) for age-related exudative macular degeneration (AMD) with regression.

PATIENTS AND METHODS

In exudative AMD with occult choroidal neovascularization (CNV), transpupillary thermotherapy (TTT) was performed using a diode laser (Iridex) in unselected patients. Before therapy and 1, 3, and 6 months after the initial treatment the patients were examined clinically. Additionally threshold testing in the 10 degrees field (Humphrey) and fluorescein angiographies were documented at all check-ups.

RESULTS

With respect to vision, differences in the slope of the regression lines between small, medium, and large CNV were significant (p<0.001). The slope of the regressions lines was significant except for small CNV. Regarding the 10 degrees field (Humphrey), there were no statistical differences in the slope of the regression lines (p=0.867).

CONCLUSIONS

Transpupillary thermotherapy with small CNV did not show a statistically significant decrease of VA. Thus, in clinical terms early treatment of occult CNV with TTT seems to be able to prevent a further loss of visual acuity.

Evolution of retinal laser therapy: minimum intensity photocoagulation (MIP). Can the laser heal the retina without harming it?

Laser photocoagulation is a photo-thermal therapy validated by landmark studies and commonly accepted as the standard of care for various retinal diseases. Although its mechanism of action is still not completely understood, it is normally administered with visible endpoints, true intra-retinal burns that cause chorioretinal scars, which, with time, evolve into expanding areas of atrophy. New hypotheses on the mechanism of action of laser photocoagulation suggest that its therapeutic benefits derive from biologic activities that cannot be inducted within the "burned" area of photocoagulation necrosis, but that occur in the adjacent surrounding areas affected by a lower, sub-lethal, photo-thermal elevation. Thus, the iatrogenic chorioretinal damage caused by visible endpoint photocoagulation may be redundant and an equally effective laser therapy could be administered with minimum intensity photocoagulation (MIP) using laser protocols aiming to create only non-lethal photo-thermal elevations with no intraoperative visible endpoint. It is the purpose of this paper to review laser techniques and clinical protocols that have been utilized to administer retina-sparing MIP treatments that hold the promise of healing the retina while minimizing the iatrogenic harm.

Transpupillare Thermotherapie bei subfovealer choroidaler Neovaskularisation

PURPOSE

The purpose of this study was to evaluate the efficiency, stability, and safety of transpupillary thermotherapy as a treatment of subfoveal occult choroidal neovascularizations (CNV) in age-related macular degeneration.

METHODS

Transpupillary thermotherapy (TTT) was performed in 40 patients with uni- or bilateral predominantly occult CNV. Laser light derived from an infrared diode laser at 810 nm was used to apply spots for a duration of 60 s. A complete ophthalmic examination was performed prior to and 9 months after the treatment.

RESULTS

After 9 months, visual acuity remained stable in 65% (+/-2 lines). In 35% of the patients TTT could not prevent further visual loss. Retinal leakage, assessed by fluorescein angiography, stabilized in 67.5% of the treated patients.

CONCLUSIONS

The present data show stabilization of visual acuity in 65% after TTT. Compared to the natural course of occult and mixed subfoveal CNV, these data give some evidence for patient benefit after TTT.

Macular infarction after transpupillary thermotherapy for subfoveal choroidal neovascularization in age-related macular degeneration

PURPOSE

To report the complication of macular infarction after transpupillary thermotherapy (TTT) for the treatment of subfoveal choroidal neovascularization (CNV) due to age-related macular degeneration (AMD).

DESIGN

Interventional case reports.

METHODS

Among 107 consecutive patients with subfoveal CNV due to AMD, a 73-year-old woman with recurrent subfoveal classic choroidal neovascularization and a 76-year-old man with subfoveal occult choroidal neovascularization with adjacent areas of geographic retinal pigment epithelium atrophy noted a severe decrease in visual acuity and photopsias within hours of undergoing TTT.

RESULTS

Both patients had marked whitening of the macula clinically and closure of the perifoveal capillaries on fluorescein angiography. Immediately after treatment their visual acuity decreased from 20/200 to 6/200 and from 20/400 to 2/200, respectively. Several months later, all exudation had resolved and their visual acuity had stabilized at 20/100 and 20/200, respectively.

CONCLUSIONS

Macular infarction is a rare complication that occurred in two of 107 patients undergoing TTT for subfoveal CNV due to AMD. The presence of geographic retinal pigment epithelium atrophy or a previous laser treatment scar in the macular region may predispose patients to this complication.