Transscleral red-laser cyclophotocoagulation combined with limited anterior retinal cryocoagulation in neovascular glaucoma

PURPOSE

To evaluate transscleral contact red-laser cyclophotocoagulation (CPC), using a visible red 647-nm krypton or 670-nm diode laser and limited transscleral anterior retinal cryocoagulation in neovascular glaucoma.

METHODS

In a retrospective case series, 35 eyes of 35 consecutive patients treated during a period of 6 years were included in the study. Inclusion was dependent on follow-up of at least 1 month. Patients who had undergone previous cyclodestructive procedures and patients who received an additional glaucoma operation in conjunction with CPC were excluded. In the combined procedure, the power per CPC application was 370-450 mW and exposure time was 10 seconds. One to two rows of cryoapplications were given to 360 degrees of the anterior retina.

RESULTS

The success rate in terms of intraocular pressure (IOP of 8-21 mmHg or a decrease in IOP > 30%) was 89% at the last follow-up (17 +/- 15 months). Iris neovascularization regressed in 51% of eyes. Hypotonia developed in one (3%) eye (IOP of 5 mmHg). No cases of phthisis bulbi were seen. Visual acuity (VA) declined in 49% of eyes.

CONCLUSIONS

A combination of transscleral contact red-laser CPC with limited anterior retinal cryocoagulation is efficient in lowering IOP in neovascular glaucoma and is well tolerated. During follow-up, a decrease in VA occurs in a significant proportion of patients.

Noninvasive optoacoustic online retinal temperature determination during continuous-wave laser irradiation

The therapeutic effect of most retinal laser treatments is initiated by a transient temperature increase. Although crucial to the effectiveness of the treatment, the temperature course is not exactly known due to individually different tissue properties. We develop an optoacoustic method to determine the retinal temperature increase in real time during continuous-wave (cw) laser irradiation, and perform temperature calculations to interpret the results exemplary for transpupillary thermotherapy (TTT). Porcine globes ex vivo and rabbit eyes in vivo are irradiated with a diode laser (lambda=810 nm, P< or =3 W, phi=2 mm) for 60 s. Simultaneously, pulses from a N2-laser pumped dye laser (lambda=500 nm, tau=3.5 ns, E approximately 5 microJ) are applied on the retina. Following its absorption, an ultrasonic pressure wave is emitted, which is detected by a transducer embedded in a contact lens. Using the previously measured temperature-dependent Gruneisen coefficient of chorioretinal tissue, a temperature raise in porcine eyes of 5.8 degrees C(Wcm2) after 60 s is observed and confirmed by simultaneous measurements with an inserted thermocouple. In a rabbit, we find 1.4 degrees C(Wcm2) with, and 2.2 degrees C(Wcm2) without perfusion at the same location. Coagulation of the rabbit's retina occurs at DeltaT=21 degrees C after 40 s. In conclusion, this optoacoustic method seems feasible for an in vivo real-time determination of temperature, opening the possibility for feedback control retinal laser treatments.

Transpupillary thermotherapy for subfoveal leaks in central serous chorioretinopathy

AIM

To evaluate transpupillary thermotherapy (TTT) for the treatment of subfoveal focal leaks in central serous chorioretinopathy (CSC).

METHODS

The patients presenting with long-standing CSC, but without the features of chronicity, were offered the options of TTT, photodynamic therapy (for subfoveal leaks), photocoagulation (for extrafoveal leaks), or observation. The patients who opted for TTT or observation were enrolled in this study. TTT was performed using a spot diameter of 0.5 mm for 1 min. Best-corrected visual acuity (BCVA), status of macular detachment, and fluorescein angiographic status were evaluated at 1, 3, and 6 months.

RESULTS

This study included 39 patients (40 eyes) with CSC between 4 and 12 months, of whom 25 patients (25 eyes) opted for TTT for subfoveal leaks. Fourteen patients (15 eyes) were followed up without treatment. The groups were comparable in age, sex, and baseline BCVA. Minimum follow-up was 6 months. Within 3 months, TTT resulted in the resolution of the serous detachment in 24 (96%) eyes with a single session; one eye required a repeat treatment. Eight control eyes demonstrated persisting CSC at the last follow-up. Visual acuity improved in 23 (92%) treated and five (33%) control eyes; the difference in outcome was statistically significant (P<0.001). One case developed choroidal neovascularization, which resolved with visual recovery to 20/20 after repeat-TTT.

CONCLUSION

TTT resulted in the resolution of CSC with subfoveal angiographic leaks with significant improvement in visual outcome, in comparison to the natural history of persistent CSC.

Absorption of diode 810 nm used for transpupillary thermotherapy by blood. An in vitro study

BACKGROUND AND OBJECTIVES

To evaluate the in vitro energy attenuation by transpupillary thermotherapy (TTT) using an 810-nm diode laser after the treatment of exudative age-related macular degeneration.

STUDY DESIGN/MATERIALS AND METHODS

In this experiment, an 810-nm diode laser was coupled to a slit lamp to deliver laser energy to a laser-power sensor adjusted in the track of the laser light. The spotlight was 0.5 mm in diameter; duration of exposure, 3 seconds. Citrated Pasteur pipettes were filled with blood diluted in saline in several concentrations and placed in the path of the laser light. The absorption of the light measured by the power sensor was tested for various delivered irradiances between 50.92 and 509.29 W/cm2. The differences were analyzed statistically.

RESULTS

There were significant differences in laser blockage comparing various conditions for all power levels (P<0.05). Increasing the proportion of blood resulted in more laser blockage with all irradiances (P<0.05).

CONCLUSIONS

Blood significantly blocks the transmission of the 810-nm diode TTT laser.

Transpupillary thermotherapy for the treatment of occult CNV in age-related macular degeneration: a prospective randomized controlled pilot study

PURPOSE

To evaluate whether transpupillary thermotherapy (TTT) reduces the risk of moderate visual loss in patients with occult choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD).

METHODS

A group of 25 patients were recruited and randomized into TTT or placebo groups. Patients were included if they had a subfoveal purely or predominantly (> 50%) occult CNV secondary to AMD with best corrected visual acuity (BCVA) of 6/60 or better and the lesion was not larger than 4.5 mm. Treatment was carried out using an 810-nm Oculight diode laser with a fixed spot size covering the whole lesion according to the standard protocol. The same procedure was used for the control group, except that the power was set at zero. The patients were followed up at 6 weeks, 3 months and then every 6 months for up to 2 years. A maximum of three treatments were administered in both groups if there was evidence of persistent leakage from CNV.

RESULTS

At the 12-month follow-up, there was no significant difference in the mean values for BCVA distance and near or contrast sensitivity between the treatment and control groups. The Mann-Whitney test was used to assess the differences in BCVA and contrast sensitivity between the groups, both at baseline and at the 12-month follow-up. No statistically significant difference was found; both groups lost on average two lines of BCVA.

CONCLUSION

Transpupillary thermotherapy appeared to have been of no benefit in preventing further visual loss in patients with occult CNV in this pilot study.

Visual function following transpupillary thermotherapy with adjusted laser parameters for the treatment of exudative age-related macular degeneration: a pilot study

PURPOSE

To evaluate the efficacy of transpupillary thermotherapy (TTT) using adjusted laser parameters for the treatment of choroidal neovascularization (CNV) secondary to age-related macular degeneration.

METHODS

TTT was performed on patients with CNV using a diode laser (810 nm) for 60 s in a subthreshold manner. Power settings were varied between 460 and 1200 mW, depending on lesion size, presence of pigment epithelial detachment and the amount of fundal pigmentation and subretinal fluid. LogMAR visual acuity, contrast sensitivity (Pelli-Robson) and metamorphopsia (Amsler chart) were assessed prior to and 6 months following treatment. Subjects also self-administered the National Eye Institute 25-Item Visual Function Questionnaire.

RESULTS

Thirty occult/minimally classic and eight predominantly classic membranes were treated with TTT. At 6 months, absence or significant reduction of fluorescein leakage was observed in 20 (53%) patients. Stabilization of vision (loss of less than 15 letters) was observed in 25/30 (83%) eyes with occult/minimally classic CNV and 5/8 (63%) eyes with predominantly classic CNV. Improvement of contrast sensitivity was noted in 15 (35%) eyes, in 10 (26%) eyes it remained unchanged and in 13 (34%) eyes it deteriorated. There was no statistically significant effect of TTT on the National Eye Institute 25-Item Visual Function Questionnaire composite or subscale scores.

CONCLUSIONS

TTT using adjusted parameters depending on fundal characteristics appears to be effective in stabilizing subjective and objective visual ability in a considerable number of patients with subfoveal CNV due to age-related macular degeneration. Larger-scale studies are required to confirm the benefit of this technique as opposed to the natural history of occult CNV.

Transpupillary thermotherapy for the treatment of choroidal neovascularization in age-related macular degeneration in Taiwan

PURPOSE

To evaluate the therapeutic outcome and the recurrence of choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) after transpupillary thermotherapy (TTT) in light-brown retinas.

METHODS

A retrospective, non-randomized study of 58 eyes in 55 patients with subfoveal CNV treated with TTT was conducted. Power settings were set about half the value for Caucasian eyes. The outcome was assessed with best-corrected visual acuity, fluorescein angiography, indocyanine green angiography, and fundoscopic examination.

RESULTS

Forty-four membranes were occult, six classic, and eight mixed. Mean follow-up was 16.6+/-10.7 months (range: 6-48 months). Membranes closed in 46 eyes. Iatrogenic complications included three subretinal haemorrhage, two retinal pigment epithelium tears, and two macular area cystic changes. In eyes with occult CNV, visual acuity improved in six (13.6%), 14 (31.8%) remained unchanged, and 24 (54.6%) deteriorated. For various CNV, average logMAR changes from baseline at last follow-up were 0.30 in occult, -0.08 in classic, and 0.59 in mixed (P<0.01). Thirty eyes experienced recurrence within 9.2+/-6.2 months (range: 2-22 months). Cumulative recurrence rate was 45% at 12 months and 71% at 22 months, with no significant difference between occult and non-occult type CNV.

CONCLUSIONS

Transpupillary thermotherapy does not cure CNV secondary to AMD. High recurrence was found independent of CNV type. Most improved vision was found mostly in classic CNV. Complications associated with high energy level should be considered in light-brown retinas.

Subthreshold transpupillary thermotherapy of the retina and experimental choroidal neovascularization in a rat model

PURPOSE

To study the effect of subthreshold transpupillary thermotherapy (TTT) on the retina and experimental choroidal neovascularization (CNV) in the rat.

METHODS

Subthreshold TTT was performed on normal Brown Norway rats or those with krypton laser-induced CNV and appropriate controls with an 810-nm diode laser coupled to a slit lamp. At different intervals after TTT, fundus fluorescence angiography (FFA) and histopathological examinations were performed. Terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) was used to detect apoptosis. Immunohistochemistry was used to detect heat shock protein 70 (Hsp70) expression.

RESULTS

In normal retina, edema and whitening was found on day 1 after TTT. Different degrees of hyperfluorescence could be seen on FFA. Obvious retina damage, especially in the outer layers, was observed by histology in all the lesions that appeared whitened. In the CNV there was congestion and less damage in the overlying retina than in normal retina on day 1 after TTT. Apoptosis was detected in all retinal layers and CNV lesions by TUNEL. In normal eyes, after TTT, Hsp70 expression was increased in the inner layers of the retina and some of the cells in the choroid. Hsp70 was also increased in laser-induced CNV. Two weeks after TTT, the CNV showed a tendency for fibrosis by Masson staining. FFA did not show much change in the CNV lesions 2 weeks after TTT.

CONCLUSION

Subthreshold TTT has adverse effects on the overlying retina and thus is likely to cause significant functional and morphological long-term sequelae. Subthreshold TTT can cause apoptosis in laser-induced CNV in rats.

EFFECTIVE TRANSSCLERAL DELIVERY OF TWO RETINAL ANTI-ANGIOGENIC MOLECULES

PURPOSE

To evaluate the human transscleral diffusion and intravitreal delivery of carboxyamido-triazole (CAI) and 2-Methoxyestradiol (2ME2).

METHODS

The transscleral diffusion of two retinal antiangiogenic molecules, CAI and 2ME2, was measured in vitro to assess their potential transscleral delivery. Varying concentrations and different solvents of CAI and 2ME2 were placed in the upper compartment of a two-chamber acrylic perfusion apparatus, on the episcleral side of the sclera obtained from human donor eyes. Samples were taken from the lower compartment (uveal side) for up to 24 hours and measured by high performance liquid chromatography.

RESULTS

All three solutions that contained CAI efficiently diffused through the sclera with permeability constants that ranged from 2.8 to 5.5 x 10 cm/s. The scleral permeability constant derived for 2ME2 was 9.96 x 10 cm/s. The permeability constants obtained for both CAI and 2ME2 are similar to each other as well as to permeability constants measured for other small molecules such as fluorescein and dexamethasone fluorescein.

CONCLUSION

Both CAI and 2ME2 traverse the sclera efficiently. These data combined with the reported inhibition of posterior segment neovascularization observed with these two molecules demonstrates that CAI and 2ME2 are good candidate molecules to treat posterior segment neovascularization by local delivery.

TRANSPUPILLARY THERMOTHERAPY

PURPOSE

To correlate changes in primate fundus after transpupillary thermotherapy (TTT) at two wavelengths.

METHODS

Twelve primate eyes were treated with TTT using a wavelength of 635 nm (n=7) or 810 nm (n=5). Laser parameters were as follows: 635 nm (spot size, 1 mm; duration, 30-8 seconds; and fluence [power over time], 20-91.4 J/cm) and 810 nm (spot size, 2 mm; duration, 60 seconds; and fluence, 96-436 J/cm). Fundus photography, fluorescein and indocyanine green angiography, and enucleation were performed at time 0 or 2 weeks after TTT for histologic analysis.

RESULTS

Threshold for fundus lesions (91.4 J/cm at 635 nm and 191 J/cm at 810 nm), acute and chronic retinal damage shown by histologic analysis (79.2 J/cm at 635 nm and 96 J/cm at 810 nm), and choroidal vessel occlusion (50 J/cm at 635 nm and 96 J/cm at 810 nm) were lower at 635 nm. Disorganization of the retina and retinal pigment epithelium was seen for both wavelengths at time 0 and 2 weeks after TTT. Occlusion of the choriocapillaris and choroidal stromal vessels was noted only in specimens obtained 2 weeks after TTT.

CONCLUSIONS

TTT resulted in acute and delayed damage to the neurosensory retina that persisted at 2 weeks. The 635-nm wavelength demonstrated a lower threshold fluence for visible fundus lesions, retinal damage, and choroidal vascular occlusion than the 810-nm laser.

Optoacoustic real-time dosimetry for selective retina treatment

The selective retina treatment (SRT) targets retinal diseases associated with disorders in the retinal pigment epithelium (RPE). Due to the ophthalmoscopic invisibility of the laser-induced RPE effects, we investigate a noninvasive optoacoustic real-time dosimetry system. In vitro porcine RPE is irradiated with a Nd:YLF laser (527 nm, 1.7-micros pulse duration, 5 to 40 microJ, 30 pulses, 100-Hz repetition rate). Generated acoustic transients are measured with a piezoelectric transducer. During 27 patient treatments, the acoustic transients are measured with a transducer embedded in an ophthalmic contact lens. After treatment, RPE damage is visualized by fluorescein angiographic leakage. Below the RPE damage threshold, the optoacoustic transients show no pulse-to-pulse fluctuations within a laser pulse train. Above threshold, fluctuations of the individual transients among each other are observed. If optoacoustic pulse-to-pulse fluctuations are present, RPE leakage is observed in fluorescein angiography. In 96% of the irradiated areas, RPE leakage correlated with the optoacoustic defined threshold value. A noninvasive optoacoustic real-time dosimetry for SRT is developed and proved in vitro and during patient treatment. It detects the ophthalmoscopically invisible laser-induced damage of RPE cells and overcomes practical limitations of SRT for use in private practice.

Circumscribed choroidal hemangioma in a Chinese patient treated using transpupillary thermotherapy: a case report

We describe the first case of a Chinese patient with circumscribed choroidal hemangioma (CCH) effectively managed using transpupillary thermotherapy (TTT). A 57-year-old man had an elevated orange-red subretinal mass with a base of 5 x 5 mm superior to the optic disc, along with serous macular detachment in the left eye. Ultrasonography depicted a mass 3 mm thick with acoustic solidity and high internal reflectivity. Fluorescein angiography showed an area of hyperfluorescence in the prearterial phase and tumor staining in the late phase, consistent with a diagnosis of CCH. Therefore, TTT (spot size, 3 mm; exposure, 1 min) was performed with a diode laser, delivered through a slit-lamp biomicroscope. The laser power was first set at 300 mW and then increased in 50-mW increments, until test shots in the mid-peripheral retina outside the lesion produced a slightly grayish appearance in the irradiated area. The tumor was covered with four overlapping laser spots and subjected to an average beam power of 400 mW. Best-corrected visual acuity increased from 20/50 before treatment, to 20/20 3 months following one session of TTT. The lesion became atrophic and the subretinal fluid disappeared. Our experience shows that TTT can be an even more effective treatment strategy for CCH in Asians than in Caucasians. In Chinese patients, the power level of the diode laser should be lower than that used in Caucasians.

Optical spectroscopy noninvasively monitors response of organelles to cellular stress

Fast and noninvasive detection of cellular stress is extremely useful for fundamental research and practical applications in medicine and biology. We discovered that light scattering spectroscopy enables us to monitor the transformations in cellular organelles under thermal stress. At the temperatures triggering expression of heat shock proteins, the refractive index of mitochondria increase within 1 min after the onset of heating, indicating enhanced metabolic activity. At higher temperatures and longer exposures, the organelles increase in size. This technique provides an insight into metabolic processes within organelles larger than 50 nm without exogenous staining and opens doors for noninvasive real-time assessment of cellular stress.

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.

Polypoidal choroidal vasculopathy: Angiographic characterization of the network vascular elements and a new treatment paradigm

Macular exudative manifestations secondary to choroidal neovascular lesions remain the leading cause of definitive visual impairment and legal blindness in the elderly. During the past decade, advances in ophthalmic imaging systems have enabled the recognition of presumed new distinct choroidal neovascular lesions that share some unique clinical and angiographic peculiarities as well as better comprehension of the pathophysiologic mechanisms related to such entities. Amongst presumed newer exudative maculopathies, polypoidal choroidal vasculopathy, which has been described as a distinct choroidal abnormality characterized by inner choroidal vascular network of vessels ending in polyp-like structures only identified on indocyanine green angiography and mostly affecting African-American and Asian descendents, has gained special interest from the ophthalmic community particularly because of its growing recognition among patients with clinical appearance of neovascular age-related macular degeneration. Thus far, however, the exact nature of the vascular structure of the polypoidal choroidal vasculopathy lesion remains unclear and data from recent studies have conflicted with the initial concept of a benign exudative maculopathy with long-term preservation of good vision. All together, such factors make difficult the establishment of an appropriate treatment, if any, for the entity. Herein, by using a modified technique of conventional indocyanine green angiography, we demonstrate new information about the morphologic characteristics, and to some extent the blood flow dynamics perfusion, of the polypoidal choroidal vasculopathy lesion. Our results suggest that the PCV lesion should be considered a variety of choroidal neovascularization rather than a distinct clinical entity, characterized by one single large neovascular complex presenting well-defined arterial neovascular vessels arising from one major "ingrowth site" and draining vessels that present aneurysm-like dilations corresponding to the polyp-like structures typically described for the entity. Finally, the visual acuity and angiographic findings observed after selective ingrowth site photothrombosis corroborate the existence of one major "ingrowth site" for the PCV neovascular complex and point toward a new treatment paradigm for this variety of choroidal neovascularization.

Changes in Foveal Thickness and Macular Function after Transpupillary Thermotherapy for Age-Related Macular Degeneration

PURPOSE

To evaluate the effect of transpupillary thermotherapy (TTT) on foveal thickness and macular function in eyes with choroidal neovascularization (CNV) associated with age-related macular degeneration.

METHODS

Sixteen eyes with occult CNV and 6 eyes with classic CNV were treated with TTT. Optical coherence tomography and focal macular electroretinograms (FMERGs) elicited by a 15-degree stimulus were performed before, 3 months after TTT in 22 eyes and 6 months after TTT in 18 eyes.

RESULTS

Before TTT, the fovea in 20 of the 22 eyes with CNV was significantly thicker than that of normal subjects. The foveal thickness was reduced after TTT in 11 of 14 eyes with occult CNV and remained unchanged in 2 eyes. One eye with occult CNV before TTT developed a classic CNV with significant macular edema and increased foveal thickness 3 months after TTT. The amplitudes of the FMERGs were reduced in all eyes before TTT. In eyes with occult CNV, the mean b-wave amplitude increased significantly after TTT (p = 0.0260 at 3 months, p = 0.0142 at 6 months). When the change of foveal thickness was less than 20% after TTT, all eyes with occult CNV had a 30% or more increase in the b-wave amplitude. In eyes with classic CNV, the mean amplitude of the a- and b-waves did not change significantly after TTT.

CONCLUSIONS

TTT improves macular function in eyes with occult CNV associated with age-related macular degeneration more when the change of foveal thickness is slight.

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.

Comparison of laser beam intensity profiles produced by photodynamic therapy (PDT) and transpupillary thermotherapy (TTT) lasers

BACKGROUND AND OBJECTIVES

For photodynamic therapy (PDT) or transpupillary thermotherapy (TTT) lasers, long irradiation time (typically 1 minute or longer) is used and a large area of retina is treated. Consequently, the power stability but also the light distribution within the laser beam plays a major role. This study aimed to evaluate beam intensity profiles produced by several PDT and TTT lasers.

STUDY DESIGN/MATERIALS AND METHODS

A beam profile analyzer (Cohu 4812 camera connected to a LPA-300PC, Spiricon, Logan, UT) was used to compare the beam profiles of PDT lasers: OPAL (Lumenis, USA); ACTIVIS (Quantel Medical, France), VISULAS (Zeiss, Germany). Spots of 2, 3, 4, and 5 mm were tested with each laser. Similarly, TTT lasers: OCULIGHT SLx (Iridex, CA) and IRIDIS trade mark (Quantel Medical, France) were evaluated with 2 and 3 mm spot diameter and power ranging from 200 to 1,000 mW.

RESULTS

PDT lasers: OPAL had a "top hat" and homogeneous profile whatever the spot size. Numerous micro-spikes and micro-nadirs of power were observed with the ACTIVIS and the VISULAS. TTT lasers: for the IRIDIS the beam shape was rather gaussian, but the homogeneity was reduced by micro-spikes of power. With the OCULIGHT Slx the beam shape was rather top hat and only few micro-spikes or micro-nadirs of power could be disclosed.

DISCUSSION

The literature tends to prove that the shape and homogeneity of the beam profile could play a role on the efficacy of the treatment.

CONCLUSION

Since PDT and TTT lasers display different beam profiles, this parameter should be carefully evaluated when performing clinical evaluations of PDT or TTT treatments.

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.

Temperature mapping of laser-induced hyperthermia in an ocular phantom using magnetic resonance thermography

Laser-induced heating in an ocular phantom is measured with magnetic resonance thermography (MRT) using temperature-dependent phase changes in proton resonance frequency. The ocular phantom contains a layer of melanosomes isolated from bovine retinal pigment epithelium. The phantom is heated by the 806-nm output of a continuous wave diode laser with an irradiance of 2.4 to 21.6 W/cm2 in a beam radius of 0.8 or 2.4 mm, depending on the experiment. MRT is performed with a 2 T magnet, and a two-turn, 6-cm-diam, circular radio frequency coil. Two-dimensional temperature gradients are measured within the plane of the melanin layer, as well as normal to it, with a temperature resolution of 1 degrees C or better. The temperature gradients extending within the melanin layer are broader than those orthogonal to the layer, consistent with the higher optical absorption and consequent heating in the melanin. The temperature gradients in the phantom measured by MRT closely approximate the predictions of a classical heat diffusion model. Three-dimensional temperature maps with a spatial resolution of 0.25 mm in all directions are also made. Although the temporal resolution is limited in the prototype system (22.9 s for a single image "slice"), improvements in future implementations are likely. These results indicate that MRT has sufficient spatial and temperature resolution to monitor target tissue temperature during transpupillary thermotherapy in the human eye.

Indocyanine green dye-enhanced micropulsed diode laser: a novel approach to subthreshold RPE treatment in a case of central serous chorioretinopathy

PURPOSE

To present a case of central serous chorioretinopathy (CSC) treated with indocyanine green (ICG) dye-enhanced subthreshold micropulsed diode laser photocoagulation. METHODS CASE REPORT: A 35-year-old man presenting with recurrent CSC with persistent serous detachment of the sensory retina in his left eye who declined treatment with a 532 nm laser. Subthreshold treatment, with no visible endpoint, was performed with an 810 nm diode laser 15 minutes after the injection of 25 mg ICG in 2 cc of 5% glucose solution. The laser energy was delivered over the active leakage sites with a sequence of repeated 500 ms "envelopes" each containing a train of 250 micropulses with 500 mW peak power at 10% duty cycle (200 micros ON and 1,800 micros OFF) and each separated by 500 ms intra-envelopes relaxation time. Due to the absence of visible laser-induced lesions, post treatment ICG digital angiographic images were taken without further dye injection to verify that the hypofluorescent spots resulting from the subthreshold laser applications coincided with the points of leakage.

RESULTS

After 7 days, the patient presented with a less hyperopic refraction, improved visual acuity, and reduction of serous neuroepithelial detachment. No signs of laser treatment were visible at fluorescein angiography. After 8 weeks, the serous neuroepithelial detachment was almost completely resolved.

CONCLUSIONS

ICG dye-enhanced subthreshold micropulsed diode laser photocoagulation appears to be a safe and effective treatment and represents a possible approach for the management of chronic CSC with persistent central serous neuroepithelial detachment. Immediate post treatment ICG angiography, without ICG reinjection, allows documenting the actual number and location of the delivered subthreshold laser applications.

Transpupillary thermotherapy (TTT) with short duration laser exposures induce heat shock protein (HSP) hyperexpression on choroidoretinal layers

BACKGROUND AND OBJECTIVES

To assess a choroidal heat shock protein hyperexpression after transpupillary thermotherapy (TTT) performed with exposures shorter than 60 seconds.

STUDY DESIGN/MATERIALS AND METHODS

Nine male pigmented rabbits were anesthetized and TTT was performed on their right eye with a 810 nm diode laser (Iridis, Quantel-Medical (France)) (spot size: 1.3 mm). Three exposure durations (60, 30, or 15 seconds) were used with three ranges of power for each duration ("high," "mild," or "low"). A series of laser impacts was delivered to the posterior pole of the retina. Left eyes were used as controls. Twenty-four hours after laser irradiation, the animals were killed and histological study was performed on chorioretinal layers. Tissue samples were fixed in formalin and embedded in paraffin. A monoclonal antibody was used to detect Hsp70 immunoreactivity (mouse IgGl, SPA-810, Stress Gen, Victoria, BC, Canada), followed by a biotinylated goat anti-mouse antibody (Dako, Glostrup, Denmark), revealed by the avidin-biotin complex (Vectastain kit, Vector Laboratries, Burlingame, CA, USA) and the AEC chromogen. Retinal structures were further identified by HES coloration.

RESULTS

During the experiments, the laser spots were not visible except for the strongest "high" powers for each exposure duration, where a whitening was discernable at the end of the laser exposures. A strong HSP70 immunoreactivity was detected in choroidal, non-pigmented cells for laser exposures lasting 60, 30, or 15 seconds with "mild" laser powers. On the contrary, rare HSP hyperexpression was detected with "high" or "low" laser powers lasting 60, 30, or 15 seconds. No HSP-70 immunoreactivity was detected on control eyes nor outside of the irradiated zones of treated eyes.

CONCLUSIONS

Transpupillary laser irradiation lasting 15, 30, or 60 seconds induces an hyperexpression of HSP on choroidal layers. This could be a basis for the use of TTT with "short" laser exposures.

The effect of indocyanine green pretreatment on the parameters of transscleral diode laser thermotherapy-induced threshold coagulation of the ciliary body

BACKGROUND AND OBJECTIVE

To study the effect of indocyanine green (ICG) pretreatment on threshold parameters of transscleral diode laser thermotherapy-induced threshold coagulation of the ciliary body. The procedure was termed 'cyclothermotherapy' based on the long duration (15-60 seconds) of diode laser application.

STUDY DESIGN/MATERIALS AND METHODS

The right eyes of nine young adult New Zealand white rabbits underwent transscleral cyclothermotherapy (TCT, Group 1), TCT following ICG pretreatment (Group 2), and external manipulation of the ciliary body alone (Group 3). Rabbits were sacrificed after 24 hours; specimens were evaluated with gross examination and light microscopy.

RESULTS

Thresholds were 30 J/cm2 (TCT) and 4.5 J/cm2 (TCT with ICG). Widespread structural damage was seen in the ciliary processes and the ciliary body in Groups 1 and 2. In Group 3, external manipulation of the ciliary body caused hemorrhage and structural damage confined to the ciliary processes.

CONCLUSION

ICG pretreatment reduced the energy necessary to cause a threshold lesion with TCT in nonpigmented rabbits.

Review Article. New treatments in age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of legal blindness in individuals 50 years and older in the developed world. Choroidal neovascularization (CNV) in exudative AMD is responsible for the majority of severe vision loss. Until recently, laser photocoagulation was the only well-established and widely accepted treatment for CNV. However, it is beneficial only for a small subset of patients, has a high rate of CNV persistence and recurrence and results in iatrogenic, collateral damage to the overlying retina. These issues make it difficult to recommend in the case of subfoveal lesions. Consequently, numerous experimental therapeutic interventions are under investigation with the common objective of destroying the CNV but leaving the foveal neurosensory retina intact. Treatment modalities can be grouped into five major categories: photodynamic therapy; radiotherapy; transpupillary thermotherapy; anti-angiogenic and angiostatic agents; and surgical intervention. The present review aims to explain the rationale behind these new treatments, analyse the evidence for their safety and efficacy, determine their stage of development and indicate in which patients they are potentially useful.

Transpupillary thermotherapy threshold parameters: funduscopic, angiographic, and histologic findings in pigmented and nonpigmented rabbits

PURPOSE

To evaluate the effect of pigmentation on threshold fluence levels, needed to produce visible and angiographic lesions, of transpupillary thermotherapy (TTT) in rabbits.

METHODS

Six pigmented and nine nonpigmented rabbits underwent TTT with an 810-nm diode laser coupled to a slit-lamp biomicroscope using a spot size of 2 or 3 mm. The power ranged from 80 to 200 mW with 1 to 3 minutes of laser exposure for pigmented rabbits and 750 to 1800 mW with 1 minute of exposure for albino rabbits. These parameters were also evaluated after compression of the globe using the contact lens to induce blanching of the optic nerve head. After the experiment, the eyes were enucleated under deep anesthesia, and the animals were killed immediately.

RESULTS

In pigmented rabbits, the threshold fluence with the 2-mm spot size was 229 J/cm2 without compression and 153 J/cm2 with compression. With the 3-mm spot size, the threshold decreased from 200 to 150 mW as the duration of exposure lengthened (2 or 3 minutes), increasing the fluence from 170 to 382 J/cm2. In nonpigmented rabbits, the threshold fluence with the 2-mm spot size was 2,865 J/cm2 without compression and 2,674 J/cm2 with compression. With the 3-mm spot size, the threshold fluence of 1,528 J/cm2 was not affected by compression. Histopathologic studies showed transretinal damage at the lowest levels necessary to achieve angiographic evidence of a treatment lesion or a barely visible funduscopic lesion at the time of treatment.

CONCLUSIONS

Nonpigmented rabbits required more than a 12-fold increase in total TTT fluence compared with pigmented rabbits with the 2-mm spot size and a ninefold increase with the 3-mm spot size. Inner and outer retinal damage was seen histopathologically at these levels.

Transpupillary thermotherapy of juxtafoveal recurrent choroidal neovascularization

PURPOSE

To evaluate the effectiveness of low power transpupillary thermotherapy (TTT) in treating juxtafoveal recurrent choroidal neovascularization (CNV) after laser photocoagulation in patients with age-related macular degeneration (ARMD).

METHODS

Eight eyes of eight patients with ARMD and juxtafoveal recurrent CNV were treated with low power TTT, delivered using an 810-nm diode laser with 350 mW, 2.0 mm spot, and 1-minute duration. Visual acuity (VA) ranged from 20/100 to 20/50. Treatment effect was evaluated by fluorescein angiography, indocyanine green angiography, and VA measurements (Early Treatment Diabetic Retinopathy Study) at 1-week, 2-week, and monthly follow-up visits.

RESULTS

No retinal damage was visible ophthalmoscopically during treatment. At the first follow-up visit, seven eyes had obliteration of CNV and one eye required a second TTT application. VA was unchanged in six eyes, improved in one eye, and worsened in one eye. Recurrences occurred in all eyes between 1 and 7 months after TTT and were treated with photodynamic therapy (PDT). More than two PDT treatments were performed in each eye in the year after recurrence.

CONCLUSIONS

Low power TTT is as able to close juxtafoveal recurrent CNV as is high power conventional laser photocoagulation but does not prevent recurrences. Further intervention with TTT in order to treat recurrences is under investigation.

Transpupillary thermotherapy threshold parameters: effect of indocyanine green pretreatment

PURPOSE

To evaluate the effect of combined treatment with systemic indocyanine green (ICG) on threshold fluence levels of transpupillary thermotherapy (TTT) in rabbits.

METHODS

Four pigmented rabbits and 13 nonpigmented rabbits were studied. TTT was performed on normal rabbit choriocapillaris using an 810-nm diode laser via slit-lamp biomicroscope delivery through a Goldmann macular lens. Laser spot size, power, and duration of laser exposure were varied to achieve a range of TTT fluences for threshold testing in both albino and pigmented rabbit fundi. Intravenous ICG pretreatment at doses of 0.41 to 10 mg/kg was initiated at varying times before TTT treatment. After the experiment, the eyes were enucleated under deep anesthesia, the animals were killed, and the eyes were prepared for light microscopy.

RESULTS

When intravenous ICG pretreatment was employed, there was a dose-dependent decrease in the TTT fluence threshold as compared with known threshold values. At threshold fluences, histopathologic sections revealed damage to all layers of the retina in addition to choriocapillaris damage.

CONCLUSION

Intravenous ICG pretreatment can be used to lower the TTT threshold fluence and irradiance required to create angiographically visible lesions in the normal rabbit choriocapillaris. Damage was seen in all layers of the retina and choriocapillaris at threshold levels when TTT was used alone or in combination with ICG pretreatment.

CME review: A cost-utility analysis of laser photocoagulation for extrafoveal choroidal neovascularization

PURPOSE

The purpose of this study was to perform a reference case (average case), cost-utility analysis of laser photocoagulation for extrafoveal choroidal neovascularization associated with age-related macular degeneration using a model incorporating patient preferences.

METHODS

Visual acuity data for patients treated and observed over a 5-year period were obtained from previously reported studies by the Macular Photocoagulation Study Group. The results from this prospective, randomized trial were incorporated in a cost-utility model using time-trade-off utility analysis and decision analysis with Markov modeling according to the recommendations of the Panel on Cost-Effectiveness in Health and Medicine. Expenditures and health care benefits were each discounted at a 3% yearly rate.

RESULTS

Laser photocoagulation therapy for extrafoveal choroidal neovascularization in age-related macular degeneration, compared with observation, resulted in a mean gain of 0.0740 quality-adjusted life-year per patient treated. The mean cost of treatment for the average patient totaled 1,715 US dollars. The cost divided by the health care benefit resulted in 23,176 year 2001 US dollars per quality-adjusted life-year gained for this procedure for a reference case. Sensitivity analyses, varying the cost, utility values, and discount parameters, resulted in dollars per quality-adjusted life-year gained ranging from 16,117 to 49,766 US dollars.

CONCLUSION

Laser photocoagulation for extrafoveal choroidal neovascularization associated with age-related macular degeneration appears to be cost-effective when compared with interventions across multiple medical specialties.

Current indications of transpupillary thermotherapy for the treatment of posterior segment diseases

Transpupillary thermotherapy has recently emerged as a therapeutic option for patients with numerous posterior segment disorders. During the past decade, it has been used for the management of benign and malignant tumors, either as sole therapy or in combination with other treatments such a plaque radiotherapy. More recently, it has been used for management of choroidal neovascularization (CNV) secondary to age-related macular degeneration. A prospective, randomized, sham-controlled multicenter clinical trial (TTT4CNV) is currently underway to evaluate the effectiveness of TTT for the management of CNV.

Selective occlusion of subfoveal choroidal neovascularization in angioid streaks by using a new technique of ingrowth site treatment

PURPOSE

To evaluate the visual and angiographic effects, as well as optical coherence tomography (OCT) findings, after a new treatment-neovascular ingrowth-site photothrombosis-in patients with subfoveal choroidal neovascularization (CNV) secondary to angioid streaks.

DESIGN

Prospective noncomparative small case series.

PARTICIPANTS

Five eyes of 5 patients with angioid streaks in whom fluorescein and conventional indocyanine green (ICG) angiography clearly demonstrated distinct CNV vessels supplying the subfoveal neovascular complex.

INTERVENTION

All five eyes were submitted to ICG-mediated photothrombosis of the neovascular ingrowth site. This novel, laser/dye-mediated technique uses large-spot, lower-intensity 810-nm light for continuous application of laser energy to ICG concentrated in vascular lesions.

MAIN OUTCOME MEASURES

Visual outcome and the results of fluorescein angiography, ICG angiography, and OCT evaluation.

RESULTS

Fluorescein and conventional ICG angiography were sufficient to identify the CNV ingrowth site, which was juxtafoveal in 2 and extrafoveal in 3 of the 5 eyes in this series. Obliteration of the entire neovascular lesion was achieved in all patients within the first hour after ICG-mediated photothrombosis of the CNV ingrowth site. At 1 week, the mean change in best-corrected visual acuity from baseline was +3.2 (+/-1.4) lines. Twelve months after treatment, visual acuity improved by 3 or more lines in all patients, and decreased leakage of fluorescein from the CNV, as well as OCT evidence of reduced or resolved retinal edema, was seen at the last follow-up visit. Major complications, such as immediate severe visual loss and retinal vessel occlusion in the early posttreatment period, were not identified in the 5 patients submitted to the procedure.

CONCLUSIONS

Photothrombosis of the CNV ingrowth site by using lower-intensity light to direct laser energy continuously after IV ICG infusion is a safe and effective technique for rapid induction of CNV hypoperfusion in selected patients and is associated with considerable improvement in visual acuity and partial restoration of the retinal architecture up to 12 months after treatment.

Selective occlusion of subfoveal choroidal neovascularization in pathologic myopia using a new technique of ingrowth site treatment

PURPOSE

To evaluate the visual and angiographic effects as well as optical coherence tomography findings after a new technique of ingrowth site treatment of subfoveal choroidal neovascularization (CNV) secondary to pathologic myopia with the use of indocyanine green (ICG)-mediated photothrombosis.

DESIGN

Interventional, noncomparative case series.

METHOD

In the setting of a tertiary referral center, patients with pathologic myopia in whom fluorescein and conventional ICG angiography demonstrated distinct CNV vessels supplying the subfoveal neovascular complex were submitted to focal ingrowth site treatment using a new therapeutic modality termed ICG-mediated photothrombosis. Prospective evaluation including visual acuity assessment, fluorescein and ICG angiography, and optical coherence tomography (OCT) evaluation was performed at weeks 1, 12, 24, and 48 after treatment.

RESULTS

Six consecutive patients (six eyes) had treatment using a single session of ICG-mediated photothrombosis at the CNV ingrowth site. Obliteration of the entire neovascular complex was achieved immediately after treatment in all patients. At last follow-up, visual acuity improvement of 1 or more Early Treatment Diabetic Retinopathy Study lines was observed in five of six patients, and fluorescein angiography showed an absence (four eyes) or minimal leakage (two eyes) from CNV. Indocyanine green angiography demonstrated selective obliteration of the neovascular complex. Accordingly, reduction of retinal edema was observed in the OCT evaluation in all patients. There was no significant complication related to the procedure.

CONCLUSIONS

The use of lower irradiances of 810- nm continuous light application and intravenous ICG infusion for neovascular ingrowth site photothrombosis induced selective CNV hypoperfusion, as demonstrated by fluorescein and ICG angiography in patients with pathologic myopia. These findings were either consistent with the visual acuity improvement observed in five of six patients or with the partial restoration of the retinal architecture seen in OCT evaluation 12 months after treatment.

Can thermal lasers promote skin wound healing?

Lasers are now widely used for treating numerous cutaneous lesions, for scar revision (hypertrophic and keloid scars), for tissue welding, and for skin resurfacing and remodeling (wrinkle removal). In these procedures lasers are used to generate heat. The modulation of the effect (volatilization, coagulation, hyperthermia) of the laser is obtained by using different wavelengths and laser parameters. The heat source obtained by conversion of light into heat can be very superficial, yet intense, if the laser light is well absorbed (far-infrared:CO(2) or Erbium:Yttrium Aluminum Garnet [Er:YAG] lasers), or it can be much deeper and less intense if the laser light is less absorbed by the skin (visible or near-infrared). Lasers transfer energy, in the form of heat, to surrounding tissues and, regardless of the laser used, a 45-50 degrees C temperature gradient will be obtained in the surrounding skin. If a wound healing process exists, it is a result of live cells reacting to this low temperature increase. The generated supraphysiologic level of heat is able to induce a heat shock response (HSR), which can be defined as the temporary changes in cellular metabolism. These changes are rapid and transient, and are characterized by the production of a small family of proteins termed the heat shock proteins (HSP). Recent experimental studies have clearly demonstrated that HSP 70, which is over-expressed following laser irradiation, could play a role with a coordinated expression of other growth factors such as transforming growth factor (TGF)-beta. TGF-beta is known to be a key element in the inflammatory response and the fibrogenic process. In this process, the fibroblasts are the key cells since they produce collagen and extracellular matrix. In conclusion, the analysis of the literature, and the fundamental considerations concerning the healing process when using thermal lasers, are in favor of a modification of the growth factors synthesis after laser irradiation, induced by an HSR. An extensive review of the different techniques and several clinical studies confirm that thermal lasers could effectively promote skin wound healing, if they are used in a controlled manner.

Transpupillary thermotherapy of predominantly occult choroidal neovascularization in age-related macular degeneration with 12 months follow-up

PURPOSE

To perform a phase I/II safety and efficacy study in order to assess the outcome following transpupillary thermotherapy (TTT) for occult choroidal neovascularization (CNV) with no or minimally classic CNV in age-related macular degeneration.

METHODS

The study comprised 113 referred patients (79 females, 34 males) aged 59-89 years (mean 77.7 years) with predominantly occult CNV. There were 49 cases of occult with no classic CNV and 64 of occult with minimally classic CNV. According to their greatest linear dimension, lesions were classified as being < 3.0 mm or > 3.0 mm. Transpupillary thermotherapy was delivered with a diode laser, emission at 810 nm, duration 60 seconds, laser power 500-800 mW. Clinical examination, ETDRS logMAR visual acuity and fluorescein angiography were carried out at baseline, and at 3, 6 and 12 months in all cases.

RESULTS

The average baseline visual acuity was 0.20 (50.6 letters). Following TTT, it was 0.12 (42.0 letters) at 6 months and 0.12 (38.0 letters) at 12 months. Visual acuity improved in 9/113 eyes (8.0%), remained unchanged in 46 (40.7%) eyes, and deteriorated in 58 (51.3%) eyes. There was no significant difference in the proportion of eyes that had lost at least 15 letters at 12 months in the subgroup of occult with no classic CNV (18/49; 36.7%) versus those with minimally classic lesions < 3.0 mm (15/39; 38.5%). However, 13/25 (52.0%) of cases with minimally classic lesions > 3.0 mm had lost at least 15 letters at 12 months (p = 0.31). The most common complications in the 46 eyes that suffered visual loss comprised subretinal progressive fibrosis (18 eyes) and atrophy of the retinal pigment epithelium (13 eyes).

CONCLUSIONS

This study shows that TTT generally prevents moderate and severe visual loss at 12 months follow-up in occult CNV with no classic CNV. Eyes with minimally classic lesions with a greatest linear dimension of < 3.0 mm also show the same positive outcome. These results compare favourably with published data on the natural course of the disease. However, minimally classic lesions of > 3.0 mm responded poorly in this treatment setting.