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Graefe's Archive for Clinical and Experimental Ophthalmology

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01-06-2015 | Retinal Disorders

Factors affecting laser power in retinal Navilas laser treatment

Authors: Alexandra E. Hoeh, Stefanie Pollithy, Stefan Dithmar

Published in: Graefe's Archive for Clinical and Experimental Ophthalmology | Issue 6/2015

Abstract

Purpose

To evaluate the effect of patient-associated factors on the minimum laser power needed for a mild visible burn in focal laser treatments using the 532 nm Navilas laser system.

Methods

We conducted a monocentric prospective pilot study of 58 eyes of 40 patients with diabetic macular edema. The following parameters were analysed: axial length, refraction, iris pigmentation, lens status, lens grading and densitometry, retinal and choroidal thickness and focus setting during treatment. Laser power was adjusted to produce mild, barely visible burns. Retinal laser burn size was measured 30 min after treatment.

Results

Focus setting is significantly correlated with retinal lesion size (r = 0.50, p = 0.001) and laser power (r = 0.44, p < 0.001). Axial length only correlated with laser power when the effect of focus was controlled. Phakic eyes needed more laser power than pseudophakic eyes (78.3 versus 67.2 mW, p = 0.051). No correlation of laser power with any other factor could be found.

Conclusions

Among the examined parameters, focus setting had the strongest effect on the laser power needed to produce a mild visible burn. The association of focus with laser power can be explained by the focus-dependent change of retinal spot size. Lens status (phakic versus pseudophakic patients) seems to influence laser light transmission in the examined age group.

Early Treatment Diabetic Retinopathy Study research group (1985) Photocoagulation for diabetic macular edema. Early Treatment Diabetic Retinopathy Study report number 1. Arch Ophthalmol 103:1796–1806CrossRef

Kernt M, Cheuteu RE, Cserhati S, Seidensticker F, Liegl RG, Lang J, Haritoglou C, Kampik A, Ulbig MW, Neubauer AS (2012) Pain and accuracy of focal laser treatment for diabetic macular edema using a retinal navigated laser (Navilas). Clin Ophthalmol 6:289–296CrossRefPubMedCentralPubMed

Kozak I, Oster SF, Cortes MA, Dowell D, Hartmann K, Kim JS, Freeman WR (2011) Clinical evaluation and treatment accuracy in diabetic macular edema using navigated laser photocoagulator NAVILAS. Ophthalmology 118:1119–1124CrossRefPubMed

Ansari-Shahrezaei S, Ergun E, Stur M (2006) The effect of axial length on photodynamic therapy. Am J Ophthalmol 141:699–702CrossRefPubMed

Pomerantzeff O, Schepens CL (1975) Variation of energy density in argon laser photocoagulation. Arch Ophthalmol 93:1033–1035CrossRefPubMed

Blumenthal EZ, Serpetopoulos CN (2000) Laser photocoagulation spot-size errors stemming from the refractive state of the surgeon’s eye. Ophthalmology 107:329–333CrossRefPubMed

Jain A, Blumenkranz MS, Paulus Y, Wiltberger MW, Andersen DE, Huie P, Palanker D (2008) Effect of pulse duration on size and character of the lesion in retinal photocoagulation. Arch Ophthalmol 126:78–85CrossRefPubMed

Koinzer S, Schlott K, Ptaszynski L, Bever M, Kleemann S, Saeger M, Baade A, Caliebe A, Miura Y, Birngruber R, Brinkmann R, Roider J (2012) Temperature-controlled retinal photocoagulation–a step toward automated laser treatment. Invest Ophthalmol Vis Sci 53:3605–3614CrossRefPubMed

Muqit MM, Denniss J, Nourrit V, Marcellino GR, Henson DB, Schiessl I, Stanga PE (2011) Spatial and spectral imaging of retinal laser photocoagulation burns. Invest Ophthalmol Vis Sci 52:994–1002CrossRefPubMed

10.

Bennett AG, Rudnicka AR, Edgar DF (1994) Improvements on Littmann’s method of determining the size of retinal features by fundus photography. Graefes Arch Clin Exp Ophthalmol 232:361–367CrossRefPubMed

11.

Littmann H (1988) Determining the true size of an object on the fundus of the living eye. Klin Monbl Augenheilkd 192:66–67CrossRefPubMed

12.

Ansari-Shahrezaei S, Binder S, Stur M (2011) The effect of laser unit on photodynamic therapy spot size. Graefes Arch Clin Exp Ophthalmol 249:11–14CrossRefPubMed

13.

Kondo M, Ito Y, Miyata K, Kondo N, Ishikawa K, Terasaki H (2006) Effect of axial length on laser spot size during photodynamic therapy: an experimental study in monkeys. Am J Ophthalmol 141:214–215CrossRefPubMed

14.

Stur M, Ansari-Shahrezaei S (2001) The effect of axial length on laser spot size and laser irradiance. Arch Ophthalmol 119:1323–1328CrossRefPubMed

15.

Bron AJ, Vrensen GF, Koretz J, Maraini G, Harding JJ (2000) The ageing lens. Ophthalmologica 214:86–104CrossRefPubMed

16.

Menon IA, Wakeham DC, Persad SD, Avaria M, Trope GE, Basu PK (1992) Quantitative determination of the melanin contents in ocular tissues from human blue and brown eyes. J Ocul Pharmacol 8:35–42CrossRefPubMed

17.

Wakamatsu K, Hu D-N, McCormick SA, Ito S (2012) Characterization of melanin in human iridal and choroidal melanocytes from eyes with various colored irides. Pigment Cell Melanoma Res 21:97–105CrossRef

18.

Schmidt SY, Peisch RD (1986) Melanin concentration in normal human retinal pigment epithelium. Regional variation and age-related reduction. Invest Ophthalmol Vis Sci 27:1063–1067PubMed

19.

Kim M, Kim SS, Kwon HJ, Koh HJ, Lee SC (2012) Association between choroidal thickness and ocular perfusion pressure in young, healthy subjects: enhanced depth imaging optical coherence tomography study. Invest Ophthalmol Vis Sci 53:7710–7717CrossRefPubMed

20.

Welch AJ, Wissler EH, Priebe LA (1980) Significance of blood flow in calculations of temperature in laser irradiated tissue. IEEE Trans Biomed Eng 27:164–166CrossRefPubMed

21.

Birngruber R, Weinberg W, Gabel V-P, Kain H (1980) Der Einfluß der aderhautdurchblutung auf die entstehung von thermischen läsionen am augenhintergrund. Ber Dtsch Ophthalmol Ges 77:705–710

22.

Geeraets WJ, Williams R, Chan G, Ham WT, Guerry D, Schmidt FH (1962) The relative absorption of thermal energy in retina and choroid. Invest Ophthalmol 1:340–347PubMed

23.

Singh A, Stewart JM (2009) Pathophysiology of diabetic macular edema. Int Ophthalmol Clin 49:1–11CrossRefPubMed

Title: Factors affecting laser power in retinal Navilas laser treatment
Authors: Alexandra E. Hoeh
Stefanie Pollithy
Stefan Dithmar
Publication date: 01-06-2015
Publisher: Springer Berlin Heidelberg
Published in: Graefe's Archive for Clinical and Experimental Ophthalmology / Issue 6/2015
Print ISSN: 0721-832X
Electronic ISSN: 1435-702X
DOI: https://doi.org/10.1007/s00417-014-2774-4

At a glance: The STEP trials

Springer Medicine

Factors affecting laser power in retinal Navilas laser treatment

Abstract

Purpose

Methods

Results

Conclusions

At a glance: The STEP trials

Springer Medicine

Abstract

Purpose

Methods

Results

Conclusions

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