Original Article

Micropulse diode laser photocoagulation forcentral serous chorio-retinopathyBhaskar Gupta MRCOphth, Mohammed Elagouz MD, Dominic McHugh FRCOphth, Victor Chong FRCOphthand Sobha Sivaprasad FRCSLaser and Retinal Research Unit, King’s College Hospital, London, UK

ABSTRACT

Purpose: Central serous chorioretinopathy (CSC) isusually characterized by a localized detachment ofthe neurosensory retina that is self-limiting. How-ever, some cases may persist or recur leading todegenerative changes of the retinal pigment epithe-lium and the neurosensory retina resulting in severevisual loss and requiring intervention.

Methods: This retrospective case series reports thelong-term visual outcome of the use of micropulselaser photocoagulation for this condition with areview of literature.

Results: The mean follow up was 17.1 months. Fourof the five patients had complete resolution of symp-toms whereas one patient had recurrent CSC from anew leak that failed to resolve after repeat micro-pulse treatment despite improvement in symptoms.

Discussion: The outcomes in this case series confirmthe long-term efficacy of micropulse laser in themanagement of CSC. It produces therapeutic effectsthat appear comparable to those of conventionalphotocoagulation with no detectable signs of laser-induced iatrogenic damage.

Key words: central serous chorioretinopathy, laserinstruments, micropulse diode laser, retinal disease.

INTRODUCTION

Central serous chorioretinopathy (CSC) is a condi-tion that is most commonly encountered in youngor middle aged adults with a male preponderance,and presents with a localized detachment of the

neurosensory retina. The natural course of thedisease is relatively benign. However, a small pro-portion of patients develop the chronic form of CSCcharacterized by persistent subretinal fluid accumu-lation at the macula for at least 6 months leading todegenerative changes of the retinal pigment epithe-lium (RPE) and the neurosensory retina resulting insevere visual loss.

Conventional argon laser treatment of the RPEleak is a therapeutic option for extrafoveal leakage.The established end-point of visible burn is associ-ated with inevitable collateral damage and mayresult in reduced contrast sensitivity, abnormalcolour vision and scotoma in the field of vision.1 Thelaser scars may also progressively enlarge (creep)and predispose to the development of choroidalneovascularization.

Photodynamic therapy (PDT) is an alternative totraditional laser treatment and can be applied to bothjuxtafoveal and subfoveal leakage. However, thisoption is also not without complications includingRPE atrophy and transient central scotoma.2

Micropulse diode (MPD) laser was first proposedfor the treatment of CSC by Bandello et al.3 In theirstudy, all five eyes had complete resorption within1 month of MPD treatment and the effect was main-tained for 4 months with no visible laser – inducedretinal changes.

Theoretically, the MPD may spare the damage tothe neural retina by raising the temperature ofthe RPE to just below the protein-denaturation-threshold so that the thermal wave that reaches theneural retina is insufficient to cause neither damagenor a clinically visible end-point (opacified retina). Itis different from subthreshold continuous wave inthat more energy can be delivered to the RPEwithout neuroretinal damage using multiple shortpulses.

� Correspondence: Miss Sobha Sivaprasad, King’s College Hospital, Denmark Hill, London SE5 9RS, UK. Email: senswathi@aol.com

Received 23 April 2009; accepted 24 August 2009.

Clinical and Experimental Ophthalmology 2009; 37: 801–805 doi: 10.1111/j.1442-9071.2009.02157.x

© 2009 The AuthorsJournal compilation © 2009 Royal Australian and New Zealand College of Ophthalmologists

In the continuous wave mode, the laser energy isdelivered with a single pulse with a duration ofexposure of 0.1–0.5 s, most of the energy is absorbedby the RPE and the heat energy is transferred to theneurosensory retina leading to transient retinalswelling (visible end-point). In the micropulsemode, the laser energy is delivered with a train ofrepetitive short pulses (typically of 0.1–0.3 milisec-onds [ms] and the duration of exposure is typically0.1–0.5 s). The ‘ON’ time is the duration of eachmicropulse. The ‘OFF’ time between successivemicropulses allows the RPE to cool down. The ratiobetween the ‘ON’ time and the total period of ‘ON’and ‘OFF’ time is the duty cycle in %. For instance,0.2 s (200 ms) of 15% duty cycle with a 2 ms pulse,the laser will deliver 100 pulses, of 0.3 ms ON (withenergy) and 1.7 ms OFF time (allowing RPEcooling).

We report the outcome of MPD in CSC in fivesubjects with a mean follow up of 17 months.

METHODS

Technique of MPD in CSC

Written consent was obtained from all patientsbefore treatment. The need for repeat treatment wasexplained. After mydriasis with tropicamide (1%)and topical anaesthesia with benoxinate (0.4%) eyedrops, an Area Centralis contact lens (Volk Opti-cals, Mentor, Lake, OH, USA) was applied. The810 nm infrared diode laser (Iris OcuLight 810SLx,

Iridex, Cwmbran, Wales, UK) was used. The treat-ment parameters were standardized to a spot size of125 mm and pulse duration of 0.2 s. An initial dutycycle of 15% was selected. Test exposures wereapplied outside the treatment area (Fig. 1c,d) andthe power increased until a threshold burn wasobtained. The power was then reduced by 20%increments until there was no visible reaction.Once the subthreshold treatment parameters wereobtained, a grid of 5–10 exposures was applied atthe area of leakage on fundus fluorescein angiogra-phy. The patients were monitored using opticalcoherence tomography (OCT) (Stratus, Carl Zeissversion 4). The FFA was repeated if the symptomspersisted with no decrease in subretinal fluid onOCT or if the CSC recurred. FFA-guided repeatMPD laser was performed on the persistent or newleak.

Case 1

A 46-year-old man with an amblyopic right eye gavea 12-month history of distortion of central vision inthe left eye. The best-corrected visual acuity was6/60 right eye (OD) and 6/12 left eye (OS). Bothbiomicroscopy and OCT confirmed subretinal fluid.MPD laser was applied to the area of focal jux-tafoveal angiographic leakage (Fig. 1a,b). The symp-toms of distortion resolved within 2 days, the centraldim area resolved in 5 days and visual acuityimproved to 6/6 OS. The visual acuity remains stableat 20-month follow up.

Figure 1. (a) FFA showing pre-treatment juxtafoveal leakage:case 1. (b) Decreased leakage posttreatment: case 1. (c) FFA show-ing pretreatment extrafovealfoveal leakage. The thresholdburns applied near the arcadecan also be visualized: case 2.(d) Decreased leakage post treat-ment: case 2.

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Case 2

A 57-year-old man gave a 12-month history ofdistortion and central blur in the right eye(best-corrected visual acuity 6/18 OD, 6/6 OS).Biomicroscopy and OCT confirmed macular CSC.The FFA showed an ink-blot leakage and ICGshowed no hot spot. MPD laser was applied in a gridmanner (10–12 subthreshold spots) without anycomplication. The symptoms decreased but subreti-nal fluid persisted at 3 months at which point FFAwas repeated and focal MPD was repeated at the siteof persistent focal leak. His symptoms improved in2 months, and at 24-month follow up there was norecurrence of CSC. The visual acuity improved to 6/6in his right eye (Fig. 1c,d)

Case 3

A 38-year-old man, artist by profession, presentedwith a 1-month history of a central visual blur in theleft eye. His best-corrected visual acuity was 6/6 ODand 6/36 OS. Biomicroscopy and OCT confirmed alarge bullous macular CSC. The FFA showed juxta-foveal ink-blot leakage. He required urgent visualimprovement and uneventful MPD laser treatmentwas applied at this stage. The symptoms resolvedcompletely within 2 months. His visual acuityimproved to 6/7.5 with no recurrence at 12 months.

Case 4

A 38-year-old man presented with a one 1-monthhistory of a central visual distortion in the left eye.His best-corrected visual acuity was 6/6 OD and 6/36OS and fundoscopy showed macular subretinalfluid. The FFA confirmed extrafoveal leakage anduneventful MPD laser treatment was undertaken.This led to resolution of symptoms within 3 months.However, the symptoms recurred 9 months later.Repeat FFA revealed new extra-foveal leak, whichwas treated by focal MPD. Although his visual acuityimproved to 6/12, he had persistent subretinal fluidat 3 months following repeat laser. No further lasertreatment has been contemplated as patient refusedany further intervention. The total length of followup is 16 months.

Case 5

A 53-year old male had experienced 2 episodes ofright CSC with disabling distortion. Although theCSC settled after 6 months on each occasion, he waskeen on treatment when he experienced his thirdepisode which was of 2 months duration. MPD laserwas applied to the area of leakage at two monthsfrom onset with a distorted visual acuity of 6/12. His

vision returned to a non-distorted 6/6 in 3 weeksand remained stable at 6-month follow up.

DISCUSSION

The pathophysiology of CSC is not completelyunderstood. Both focal and diffuse impairment ofRPE cells have been postulated to be responsible forCSC.4,5 Generally, good recovery of vision occurs inuncomplicated cases. However, poor visual recoverymay be associated with advanced age, multiplerecurrences, bullous retinal detachment, persistentneurosensory retinal detachment and choroidalneovascularization or fibrosis.6–8

Laser treatment for the management of CSC hasremained a controversial issue given the goodnatural history of the disease. Complications relatedto the use of argon green laser treatment includeaccidental photocoagulation of macula, foveal distor-tion, scotomas, significant loss of contrast sensitivity,and a 2–10% risk of developing choroidal neovascu-larization within several weeks to months aftertreatment.9–11

Photodynamic therapy (PDT) has recently beenadvocated as a treatment modality for chronic CSCwith 81–89.6% showing complete resolution of CSCfollowing treatment.12 However, the treatment is notentirely innocuous and has complications, whichinclude atrophy of the RPE, ischaemia of the chorio-capillaris and choroidal neovascularization. In viewof this, various modifications of PDT have beenattempted, including using half the dose of Vertepor-fin, laser application sooner after the infusion ceasesand a treatment zone of restricted size in comparisonto the standard PDT protocol for neovascular maculardegeneration.13 The RPE changes induced by PDTalso remain an issue.

The outcome of treatment from our case seriesconfirms the efficacy of MPD in the management ofCSC. The series indicates that it may not be neces-sary to wait for 6 months before the application ofMPD as demonstrated in case 3. Rapid resolutionmay possibly limit further damage to the RPE buteven this is speculative. Patients with chronic CSCoften have multifocal disease.

It is useful to perform ICG especially in the olderage group to rule out polypoidal vasculopathy. Someinvestigators have performed MPD treatment overICG-stained RPE cells to enhance the selectivity of thetreatment for the active leaking sites while sparingthe neurosensory retina.14 Nevertheless, good resultscan be attained with FFA-guided MPD treatment.

All studies on MPD laser treatment for CSCsupport the hypothesis that it produces therapeuticbenefits comparable to those of conventional pho-tocoagulation with no detectable signs of laser-induced iatrogenic damage14–17(Table 1).

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Although the clinical outcomes are good, thegreatest limitation of MPD laser procedures is thedifficulty to titrate treatment given that there is noophthalmoscopically visible end-point to confirmtherapy. Therefore, there are inherent risks ofre-treatment of the same areas increasing the risk ofchoroidal neovascularization.

Moreover, the biological mechanisms involved inthe beneficial effect of laser photocoagulation remainunclear. The comparative results obtained with bothMPD and conventional laser in various conditionsindicate that the energy delivered to the RPE may bean important factor. So, it can be argued that a similareffect can be produced by turning power down inconventional green laser photocoagulation toproduce the same effect.

Another observation is that, although the effect ofMPD laser is comparable to that of conventional

laser, the effects are slower. Further investigation ofmacular function by microperimetry, electrophysiol-ogy and fundus autofluorescence may give addi-tional useful information about the effects of slowresorption and long-term post-treatment stability ina larger case series.

Micropulse diode laser may have a role in themanagement of chronic CSC, as well as in acute CSCwhere urgent visual rehabilitation is required.Although titration of the dose is difficult and the effectlikely slower than conventional laser, the micropulsedelivery technique may reduce collateral damage.

REFERENCES

1. Maeshima K, Utsugi-Sutoh N, Otani T et al. Progressiveenlargement of scattered photocoagulation scars in dia-betic retinopathy. Retina 2004; 24: 507–11.

Table 1. Studies showing outcome after micropulse diode laser for central serous chorioretinopathy

Author(s) (year) Study design and no. of eyes Results

Ricci et al. (2004)14 Case report After 1 week, the VA improved.1 eye After 8 weeks, complete resolution of serous

detachment followed.No signs of laser treatment were visible at FA.

Ricci et al. (2008)17 Prospective, interventional, case series Within 2 weeks, all patients showed improved VA.7 eyes Within 8 weeks, the serous detachment was com-

pletely resolved in 5 patients and reduced in 2patients on OCT.

Patients with CSC > 6 months Minimum follow up 12 months.ICG guided MPD done

Lanzetta et al. (2008)16 Prospective, interventional, case series 14 eyes were treated once, 9 eyes received 2–3treatments, 1 eye had 5 treatments during3 years.

24 eyes SRF improved or resolved in 2/3 after 1 month,and in 3/4 at the end of follow up.

Patients with CSC > 3 m Median VA was 6/9.6 before treatment, and 6/7.5at the end of follow up.

No evidence of RPE or retinal changes due to lasertreatment.

Follow up: 3–36 months (mean 14 months).

Chen et al. (2008)15 Prospective, interventional, case series Group I: all patients had total resorption of SRFafter one session.

Total 26 eyes Group II: 8/9 had the same result, one patient hadpersistent SRF.

3 groups of patients with chronic CSC and juxtafovealleakage of >4 months.

Group III: 5/11 had SRF resorption at the end offollow up. The other 6 needed PDT for final SRFresorption.

Group I: patients with point source of leakagewithout associated RPE atrophy (6 patients).

VA gain of �3 lines achieved in 15 eyes (57.7%),1–3 lines in 6 eyes (23.1%).

Group II: patients with point source of leakagewith associated RPE atrophy (9 patients).

Mean follow up is 6 months

Group III: patients with diffuse RPEdecompensation (11 patients).

CSC, central serous chorioretinopathy; FA, fundus fluorescein angiography; ICG, indocyanine green angiography; MPD, micropulsediode; OCT, optical coherence tomography; PDT, photodynamic therapy; RPE, retinal pigment epithelium; SRF, subretinal fluid; VA, visualacuity.

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2. Postelmans L, Pasteels B, Coquelet P et al. Severepigment epithelial alterations in the treatment areafollowing photodynamic therapy for classic choroidalneovascularization in young females. Am J Ophthalmol2004; 138: 803–8.

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16. Lanzetta P, Furlan F, Morgante L et al. Nonvisible sub-threshold micropulse diode laser (810 nm) treatmentof central serous chorioretinopathy. A pilot study. EurJ Ophthalmol 2008; 18: 934–40.

17. Ricci F, Missiroli F, Regine F et al. Indocyanine greenenhanced subthreshold diode-laser micropulse pho-tocoagulation treatment of chronic central serouschorioretinopathy. Graefes Arch Clin Exp Ophthalmol2009; 247: 597–607.

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