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   Table of Contents      
ORIGINAL ARTICLE
Year : 2004  |  Volume : 52  |  Issue : 1  |  Page : 45-49

Transpupillary thermotherapy for choroidal neovascular membrane in age related macular degeneration


Sankara Nethralaya, Chennai, India

Correspondence Address:
M Agarwal
Sankara Nethralaya, Chennai
India
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Source of Support: None, Conflict of Interest: None


PMID: 15132379

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  Abstract 

Purpose: To evaluate the efficacy of transpupillary thermotherapy (TTT) in choroidal neovasularisation (CNVM) secondary to age related macular degeneration ( AMD).
Material and methods: Retrospective, non-randomized study of 28 eyes of 28 patients with subfoveal CNVM (classic, occult or mixed) secondary to AMD.
Results: Fifteen patients (53.57%) maintained their pre-treatment vision, 2 (7.14%) patients showed improvement of more than 2 lines and 11(39.28%) patients showed deterioration of vision by >2 lines. Angiographic and clinical regression of CNVM was noted in 19 patients (67.8%) on an average follow up of 15.32 3.31 months.
Conclusion: TTT leads to stabilisation of vision in 60% of treated eyes with CNVM due to AMD.

Keywords: Transpupillary thermotherapy, Age-related macular degeneration, choroidal neovascular membrane


How to cite this article:
Agarwal M, Shanmugam MP, Gopal L, Shetty N, Bhende M, Gopal L, Sharma T, Thakur S, Raman R, Nizamuddin S H, Moorthy K R. Transpupillary thermotherapy for choroidal neovascular membrane in age related macular degeneration. Indian J Ophthalmol 2004;52:45-9

How to cite this URL:
Agarwal M, Shanmugam MP, Gopal L, Shetty N, Bhende M, Gopal L, Sharma T, Thakur S, Raman R, Nizamuddin S H, Moorthy K R. Transpupillary thermotherapy for choroidal neovascular membrane in age related macular degeneration. Indian J Ophthalmol [serial online] 2004 [cited 2019 Jul 19];52:45-9. Available from: http://www.ijo.in/text.asp?2004/52/1/45/14632



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Age-related macular degeneration (AMD) is one of the leading causes of retinal blindness in patients older than 50 years of age, and the "wet" form of AMD most often leads to severe visual loss.[1]

Various treatment modalities are currently available for the management of subfoveal choroidal neovascular membrane (CNVM), including, radiotherapy, laser photocoagulation, indocyanine dye-enhanced diode laser photocoagulation, transpupillary thermotherapy (TTT), photodynamic therapy (PDT), submacular surgery, macular translocation and retinal pigment epithelium (RPE) cell transplantation. The most widely used modalities are laser photocoagulation for extrafoveal and juxtafoveal CNVM and TTT or PDT for subfoveal CNVM. [2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14]The Macular Photocoagulation Study (MPS) Group has shown that laser photocoagulation of extrafoveal and juxtafoveal CNVM reduces the risk of severe visual loss. [3],[4],[5],[6],[7]The MPS group has also shown that laser photocoagulation of subfoveal CNVM leads to long-term stability of vision in treated patients as compared to those who did not undergo treatment. However, laser photocoagulation of subfoveal CNVM is associated with immediate loss of vision, which is unacceptable to most patients. Recurrence and persistence of CNVM also compromises the benefit from treatment in a number of cases.

TTT is a technique that delivers heat to the choroid and RPE using a large spot size, low power, and long exposure infrared laser. Reichel et al were the first to report stabilisation of vision following TTT in occult CNVM due to age-related macular degeneration.[9]

We report an analysis of 28 eyes of 28 patients who underwent TTT for subfoveal CNVM due to AMD, determining its efficacy as a treatment modality.


  Materials and methods Top


Retrospective analysis of 28 eyes of 28 patients [Table - 1] with subfoveal CNVM (occult, classic, mixed) secondary to AMD and treated with TTT during July 1999 to June 2000 and a minimum follow-up of one year was performed. Details such as age at presentation, gender, and clinical features including best-corrected Snellen visual acuity, size of the CNVM, type of CNVM, presence or absence of subretinal fluid, exudates, subretinal haemorrhage prior to TTT and at follow-up visits were analysed. The size of the CNVM and leakage was compared between the pre and post TTT visits. The membranes, which showed some areas of classic and some areas of occult, were considered mixed membranes.

TTT was performed as described in the literature.9 In brief, the technique was as follows: The pupil was dilated with phenylephrine (5%) and tropicamide (0.8 %) eye drops. The treatment was performed under topical anaesthesia (proparacaine 0.5%) using infrared diode laser at 810 nm (Oculight SL Diode photocoagulator; Iridex CA with large spot adaptor) with an adjustable beam width of 0.8mm, 1.2mm and 2mm through a contact lens (Mainster lens: Ocular Instruments, Bellevue, WA, USA). Keeping in mind the pigmented fundi of the Asian Indian population, the initial power for the test burn was started from 300 mW for 2mm spot size and 200mW for 1.2mW spot size; if reaction was not obtained at this power, it was increased in 100 mW increments until the desired reaction was seen. A test burn was placed beyond the arcades and an untreated area was used to test each increment in power. Mild graying after one-minute was used to titrate the power. The largest spot size that could cover the CNVM completely was used for treatment. In case of membranes larger than 2mm, multiple, nearly overlapping burns were used. When using multiple spots for treatment, the burns were spaced at one-minute intervals to allow the heat to dissipate before placing the adjacent burn. Care was taken to avoid overlap of burns in the foveal region . The follow-up protocol was 3 months, 6 months and 1 year after the first sitting of TTT.

Clinical regression of CNVM was defined as lack of growth or reduction in the size of CNVM, reduction in the subretinal fluid, haemorrhages and exudates. Angiographic regression was defined as reduction in the size of the CVNM, and decreased dye leakage in late angiograms. If recurrence or persistence of the CNVM was suspected clinically at the follow up visits fundus fluorescein angiography was repeated. Treatment success was defined as maintenance of vision, at the same level, improvement or deterioration by one line in comparison to the pre-treatment visual status.

Persistence of subretinal fluid, subretinal haemorrhage, and exudates and/or active dye leak on fundus fluorescein angiography (FFA) in the area of the original CNVM, three months after TTT was considered persistent CNVM. Documented resorption of subretinal fluid and exudates with staining of the scar on angiography after TTT with subsequent recurrence of subretinal fluid, and subretinal haemorrhage or exudates beyond the previously treated area along with active dye leakage on angiography on subsequent follow-up was considered recurrence of CNVM. Persistence or recurrence of CNVM on follow up was treated with repeat TTT therapy. Retreatment was done at an interval of 3 months or later, from the first sitting of TTT depending upon the activity of the CNVM.


  Results Top


Of the 28 patients, 18 were males and 10 females. The mean age at presentation was 67.46 8.2 years (range: 55 - 85 years). The average follow-up was 15.32 3.31 months. 7 CNVM were classic, 7 mixed and 14 occult. The mean pre-treatment size of the CNVM was 1.8DD range (0.25 - 4DD), 14 were > 1.5DD in size. Mean power used was 446 mW 120mW (range: 300 - 700mW), for an average duration of 5.16 3.33 minutes (range: 1-14 min) and an average spot size of 1.94 mm 0.20mm (range: 1.2 - 2 mm). All the cases had undergone pre-treatment angiography. 14 of 28 eyes underwent FFA at the last visit (1 mixed, 10 occult, 3 classic).

Vision was maintained in 15 patients (53.57%), 2 (7.14%) had improved vision by more than 2 lines and 11 (39.28%) showed deterioration of vision by more than 2 lines. The average gain of lines was 0.6 lines and the average loss was 0.9 lines.

Clinical or angiographic regression of CNVM was noted in 19 patients (67.8%) at final follow up [Figure - 1][Figure - 2]. There was resorption of subretinal fluid in 21 patients (75%), exudates in 25 patients (89%) and subretinal haemorrhages in 21 patients (75%). Clinical regression was noted in 8 occult CNVM, 5 classic CNVM, and 6 mixed CNVM. In the 14 eyes which underwent angiography for suspected persistence or recurrence of CNVM, 5 showed signs of regression (1 classic, 4 occult) at the final follow-up visit.

The average number of treatment sessions required was 1.8 1 (range: 1 - 4 sessions). Twelve patients demonstrated regression of CNVM after one treatment. The average time of scarring (angiographic / clinical) after a single treatment session was 6.54 4.3 months (range: 1 -17 months).

There was angiographic persistence or recurrence of CNVM in 9 (32.14%) of 28 patients, (6 occult, 2 classic and 1 mixed membrane) at the last follow up. However, the number of patients is too small to confidently comment on the results of analysis of recurrent or persistent membranes.


  Discussion Top


TTT is long duration, low energy thermal laser treatment, performed through a specially designed large spot laser delivery system. The slow increase in temperature with the subthreshold energy, causes selective occlusion of the CNVM with relative sparing of the overlying retina and the underlying RPE. Hence it is likely to be less destructive than conventional thermal laser photocoagulation.

Our study shows that TTT leads to the stabilisation or improvement of vision in 17 of 28 (60.7%) patients, and a clinical or angiographic regression of CNVM in 19 of 28 (67.8%) treated patients at longer than one year follow up. Fewer of our patients achieved visual stability as compared to earlier reports of Reichel et al, Okada et al and Newsom et al.[9],[15],[16] These reports have shown that vision is stable

ilised in up to 75% of patients and CNVM regressed in up to 94% of patients. This difference may be attributable to the learning curve in power titration for Asian Indian pigmented fundii, longer follow up of patients in this study as compared to those reported earlier or a racial difference in behaviour of CNVM.

Several complications have been reported following TTT for uveal tumours, but the low power settings used in TTT for CNVM make complications rare. In our series one patient had a complication, this was chorioretinal atrophy on follow up.

Thus, TTT appears to have a definite role in the treatment of CNVM secondary to AMD. Its advantages are (1) absence of photosensitisation or dye-related problems associated with PDT, (2) reproducible results, (3) less collateral damage to adjacent retina compared to photocoagulation, (4) no post-treatment restrictions, and (5) finally, it would be affordable to a larger population of AMD patients in a developing country like India . The limitations of our study are that it is retrospective and non-randomised. But it does present longterm results of TTT in Asian Indian eyes, which is not reported often.

The precise role of TTT in the treatment of CNVM needs to be further defined by multi-centre randomised trials. Such a study (TTT4CNVM) is currently under way and is likely to throw more light on the role of TTT in AMD

 
  References Top

1.
Green WR, Enger C. Age related macular degeneration histopathologic studies:the 1992 Lorenz E. Zimmerman Lecture. Ophthalmology 1993;100:1519-35.  Back to cited text no. 1
    
2.
Finger PT, Chakravathy U, Augsburger JJ. Radiotherapy and the treatment of age related macular degeneration. External beam radiation therapy is effective in the treatment of age related macular degeneration. Arch Ophthalmol 1998;116:1507-11.  Back to cited text no. 2
    
3.
Macular Photocoagulation Study Group. Visual outcome after laser photocoagulation for subfoveal choroidal neovascularization secondary to age related macular degeneration. Arch Ophthalmol 1994;112:480-88.  Back to cited text no. 3
    
4.
Macular Photocoagulation Study Group. Visual outcome after laser photocoagulation for subfoveal choroidal neovascularization secondary to age related macular degeneration: The influence of initial lesion size and initial visual acuity. Arch Ophthalmol 1994;112:480-88.  Back to cited text no. 4
    
5.
Macular Photocoagulation Study Group. Visual outcome after laser photocoagulation for subfoveal choroidal neovascularization secondary to age related macular degeneration. Arch Ophthalmol 1996;114:400-12.  Back to cited text no. 5
    
6.
Macular Photocoagulation Study Group. Argon laser photocoagulation for neovasular maculopathy: Five-year results from randomized clinical trials. Arch Ophthalmol 1990;108:816-24.  Back to cited text no. 6
    
7.
Macular Photocoagulation Study Group. Krypton laser photocoagulation for neovascular lesions of age related macular degeneration. Results of a randomized clinical trial. Arch Ophthalmol 1990;108:816-24.  Back to cited text no. 7
    
8.
Reichel E, Puliafito CA, Duker JS, Guyer DR. Indocyanine green dye-enhanced diode laser photocoagulation of poorly defined subfoveal choroidal neovascularization. Ophthalmic Surg 1994;25:195-201.  Back to cited text no. 8
[PUBMED]    
9.
Reichel E, Berrocal AM, Ip Michael, Kroll AJ, Desai V, Duker JS, et al. Transpupillary thermotherapy of occult subfoveal choroidal neovascularization in patients with age-related macular degeneration. Ophthalomology 1999;106;1908-14.  Back to cited text no. 9
    
10.
Treatment of age-related macular degeneration with photodynamic therapy of subfoveal choroidal neovascularization in age related macular degeneration with verteporfin: One-year results of 2 randomized clinical trials. TAP Report No.1. Arch Ophthalmol 1999;117:1329-45.  Back to cited text no. 10
    
11.
Treatment of Age-related Macular Degeneration With Photodynamic therapy (TAP) of subfoveal choroidal neovascularization in age related macular degeneration with verteporfin: two-year results of 2 randomized clinical one-year results of 2 randomized clinical trials: TAP report No.2. Arch Ophthalmol 2001;119:198-207.  Back to cited text no. 11
    
12.
Verteporfin Therapy of Subfoveal Choroidal Neovascularization in Patients With Age-Related Macular degeneration. TAP report No.3. Arch Ophthalmol 2002;120:1443-54.  Back to cited text no. 12
    
13.
Verteporfin in Photodynamic therapy Study Group. Photodynamic therapy of subfoveal choroidal neovascularization in pathologic myopia with verteporfin: one-year results of a randomized clinical trial. VIP report 1. Ophthalmology 2001;108:841-52.   Back to cited text no. 13
    
14.
Verteporfin in Photodynamic therapy Study Group. Verteporfin therapy of subfoveal choroidal neovascularization in age-related macular degeneration; two year results of a randomized clinical trial including lesions with occult with no classic choroidal neovascularization. VIP report 2. Am J Ophthalmol 2001;131:541-60.  Back to cited text no. 14
    
15.
Okada AA, Morimura Y, Hayashi A, Hirakata A, Tano Y, Hida T. Transpupillary Thermotherapy for Subfoveal Choroidal Neovascularization in Japan. Poster presentation, American Academy of Ophthalmology. October 22-25, 2000.  Back to cited text no. 15
    
16.
Newsom RSB, McAlister JC, Saeed M, McHugh JDA. Transpupillary thermotherapy (TTT) for the treatment of choroidal neovascularization. Br J Ophthalmol 2001;85:173-78.  Back to cited text no. 16
    


    Figures

  [Figure - 1], [Figure - 2]
 
 
    Tables

  [Table - 1]


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