Ophthalmic Surgery, Lasers and Imaging Retina

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Imaging 

Fourier-Domain Optical Coherence Tomography Findings in Welder’s Maculopathy

Suman Pilli, MS; Muralidhar Ogoti, MS; Vishwanath Kalluri, MS

Abstract

Welder’s maculopathy represents a form of photochemical damage to the retina and is characterized by involvement of the outer retinal layers. Fourier-domain optical coherence tomography (FD OCT) imaging was performed in 5 eyes of 3 patients with clinical findings suggestive of welder’s maculopathy in occupational welders. Clinical examination was characterised by a faceted foveal lesion and the FD OCT line scan images showed a distinct discontinuity of the photoreceptor inner and outer segment (IS/OS) junction. The external limiting membrane (ELM) and the retinal pigment epithelial (RPE) layer remained intact at the site of IS/OS defect. FD OCT imaging offers a non-invasive way of evaluating the microstructural changes at the fovea in welder’s maculopathy.

Abstract

Welder’s maculopathy represents a form of photochemical damage to the retina and is characterized by involvement of the outer retinal layers. Fourier-domain optical coherence tomography (FD OCT) imaging was performed in 5 eyes of 3 patients with clinical findings suggestive of welder’s maculopathy in occupational welders. Clinical examination was characterised by a faceted foveal lesion and the FD OCT line scan images showed a distinct discontinuity of the photoreceptor inner and outer segment (IS/OS) junction. The external limiting membrane (ELM) and the retinal pigment epithelial (RPE) layer remained intact at the site of IS/OS defect. FD OCT imaging offers a non-invasive way of evaluating the microstructural changes at the fovea in welder’s maculopathy.

Fourier-Domain Optical Coherence Tomography Findings in Welder’s Maculopathy

From the Pushpagiri Vitreo-Retina Institute (SP, MO, VK), Secunderabad, India; and University of California (SP), Davis, Sacramento, California.

The authors have no financial or proprietary interest in the materials presented herein.

Address correspondence to Dr. Suman Pilli, Ophthalmology Department, 4860 Y Street, Suite 2400, Sacramento, CA-95817. E--mail: sumandoc2000@yahoo.com

Accepted: October 16, 2009
Posted Online: March 09, 2010

Introduction

Photochemical retinal injuries are known to occur in welder’s maculopathy, solar retinopathy, and following exposure to laser and operating microscope lights.1 Although, the source of light toxicity is different, these entities are known to share similar slit-lamp biomicroscopic findings and histopathological changes.1,2 The photochemical retinal damage in welder’s maculopathy is caused primarily by the blue end of the visible spectrum.3 The described clinical findings include reddish, well circumscribed, faceted lesion involving the foveola and juxtafoveolar area.3 In our study, we used combined Fourier-domain Optical Coherence Tomography/Scanning laser ophthalmoscope (FD OCT/SLO) machine from Ophthalmic Technologies Inc, Canada (OTI) with an image resolution of 5 to 6 microns to evaluate the microstructural changes at the fovea in welder’s maculopathy. All patients underwent line scan imaging with an A scan density upto 4000 scans per B scan.

Case Reports

Case 1

A 36-year-old man presented with complaints of defective vision in his right eye (OD) since 15 days and left eye (OS) since 3 years. He had been an occupational welder for 13 years and had stopped welding work a few years ago. He was informed regarding his retinal damage in both eyes about 3 years back. On examination, his best corrected visual acuity (BCVA) was 6/24 in right eye and 6/9 in left eye. The anterior segment examination was unremarkable in both eyes. Dilated fundus biomicroscopy of the right eye showed a serous detachment involving the macula and the left eye showed a round, faceted lesion involving the fovea. Fundus flourescein angiography (FFA) showed a focal leak in the right eye, and the left eye showed subtle transmission defects within the fovea (Fig. 1: Top right and left). This confirmed the diagnosis of central serous chorioretinopathy (CSC) in his right eye. No active intervention was advised as he had been symptomatic for past 15 days. At 3 months follow-up, the right eye BCVA improved to 6/9 and the macula showed complete resolution of subretinal fluid, retinal pigment epithelial defects temporal to fovea and a faceted lesion at the fovea. The left eye showed no change, as noted in the red free photographs of both eyes (Fig. 1: middle left and bottom left). FD OCT line scan images of both eyes (Fig. 1: middle right and bottom right) revealed a distinct discontinuity of the inner and outer segment (IS/OS) junction corresponding to the foveal lesion. The external limiting membrane (ELM) and the retinal pigment epithelium (RPE) layer remained intact at the site of IS/OS defect in both eyes. The right eye also showed RPE irregularities temporal to fovea from resolved CSC (Fig. 1: Middle right).

(Top Left) Late Phase of the Fundus Florescein Angiography (FFA) of the Right Eye (RE) Showing a Focal Leak and (top right) Left Eye (LE) Showing a Subtle Transmission Defects at the Fovea. (Middle Left) Red Free Fundus Photograph of the RE Showing a Round, Faceted Lesion at the Fovea. (Middle Right) Fourier-Domain Optical Coherence Tomography (FD OCT) Line Scan with Scanning Laser Ophthalmoscope (SLO) Image of the RE Showing a Defect in the Inner and Outer Segment (IS/OS) Junction. The External Limiting Membrane (ELM) (white Arrow Head Marks the ELM Layer) and the Retinal Pigment Epithelial (RPE) Layer Remain Intact at the Site of IS/OS Defect. The White Arrow (bold) Shows the Area of RPE Irregularities. (Bottom left) Red Free Fundus Photograph of the LE Showing a Round, Faceted Lesion at the Fovea. (Bottom Right) FD OCT Line Scan with SLO Image of the LE Showing the Defect in the IS/OS Junction with Intact ELM and RPE Layer at the Site of IS/OS Defect.

Figure 1. (Top Left) Late Phase of the Fundus Florescein Angiography (FFA) of the Right Eye (RE) Showing a Focal Leak and (top right) Left Eye (LE) Showing a Subtle Transmission Defects at the Fovea. (Middle Left) Red Free Fundus Photograph of the RE Showing a Round, Faceted Lesion at the Fovea. (Middle Right) Fourier-Domain Optical Coherence Tomography (FD OCT) Line Scan with Scanning Laser Ophthalmoscope (SLO) Image of the RE Showing a Defect in the Inner and Outer Segment (IS/OS) Junction. The External Limiting Membrane (ELM) (white Arrow Head Marks the ELM Layer) and the Retinal Pigment Epithelial (RPE) Layer Remain Intact at the Site of IS/OS Defect. The White Arrow (bold) Shows the Area of RPE Irregularities. (Bottom left) Red Free Fundus Photograph of the LE Showing a Round, Faceted Lesion at the Fovea. (Bottom Right) FD OCT Line Scan with SLO Image of the LE Showing the Defect in the IS/OS Junction with Intact ELM and RPE Layer at the Site of IS/OS Defect.

Case 2

A 34-year-old man presented with a history of diminution of vision in his right eye for 5 months. He was an occupational welder since 11 years. He had undergone phacoemulsification with intraocular lens implantation surgery in his right eye a year ago for complaints of diminished vision. On examination, the BCVA of right eye was 6/24 and the left eye was 6/6. The anterior segment examination of the right eye showed the presence of posterior chamber intraocular lens (IOL) and the left eye was unremarkable. Fundus examination of the right eye showed an elliptical, faceted lesion involving the fovea (Fig. 2: left) and the left eye showed RPE mottling at the fovea. FD OCT line scan image (Fig. 2: right) of the right eye revealed a distinct discontinuity of the IS/OS junction and intact ELM and RPE layer at the site of IS/OS defect.

(Left) Red Free Fundus Photograph of the Right Eye (RE) Showing Elliptical, Faceted Lesion at the Fovea. (Right) Fourier-Domain Optical Coherence Tomography (FD OCT) Line Scan with Scanning Laser Ophthalmoscope Image Showing a Defect in the Inner and Outer Segment (IS/OS) Junction, the External Limiting Membrane (ELM) (white Arrow Head) and the Retinal Pigment Epithelial (RPE) Layer Remain Intact at the Site of IS/OS Defect.

Figure 2. (Left) Red Free Fundus Photograph of the Right Eye (RE) Showing Elliptical, Faceted Lesion at the Fovea. (Right) Fourier-Domain Optical Coherence Tomography (FD OCT) Line Scan with Scanning Laser Ophthalmoscope Image Showing a Defect in the Inner and Outer Segment (IS/OS) Junction, the External Limiting Membrane (ELM) (white Arrow Head) and the Retinal Pigment Epithelial (RPE) Layer Remain Intact at the Site of IS/OS Defect.

Case 3

A 23-year-old man presented with complaints of defective vision in both eyes of 1 year duration, left being more symptomatic than the right eye. He was an occupational welder and duration of welding work was not known. On examination, his BCVA was 6/12 in both eyes. The anterior segment examination was otherwise normal in both eyes. Dilated fundus examination of both eyes showed a faceted lesion at the fovea, similar to the two previous cases (Fig. 3: top left and bottom left). FD OCT line scan images showed a distinct discontinuity of the IS/OS junction with intact ELM and RPE layer at the site of IS/OS defect in both eyes, and in the left eye IS/OS defect appears bigger in comparison to the right eye correlating with his visual symptoms (Fig. 3: top right and bottom right).

(Top Left) Color Fundus Photograph of the Right Eye (RE) Showing Round, Faceted Lesion at the Fovea. (Top right) Fourier-Domain Optical Coherence Tomography (FD OCT) Line Scan with Scanning Laser Ophthalmoscope (SLO) Image of the RE Showing a Defect in the Inner and Outer Segment (IS/OS) Junction, the External Limiting Membrane (ELM) (white arrow head) and the Retinal Pigment Epithelial (RPE) Layer Remain Intact at the Site of IS/OS Defect. (Bottom left) Color Fundus Photograph of the Left Eye (LE) Showing a Round, Faceted Lesion at the Fovea. (Bottom right) FD OCT Line Scan with SLO Image of the LE Showing the Defect in the IS/OS Junction with Intact ELM and RPE Layer at the Site of IS/OS Defect.

Figure 3. (Top Left) Color Fundus Photograph of the Right Eye (RE) Showing Round, Faceted Lesion at the Fovea. (Top right) Fourier-Domain Optical Coherence Tomography (FD OCT) Line Scan with Scanning Laser Ophthalmoscope (SLO) Image of the RE Showing a Defect in the Inner and Outer Segment (IS/OS) Junction, the External Limiting Membrane (ELM) (white arrow head) and the Retinal Pigment Epithelial (RPE) Layer Remain Intact at the Site of IS/OS Defect. (Bottom left) Color Fundus Photograph of the Left Eye (LE) Showing a Round, Faceted Lesion at the Fovea. (Bottom right) FD OCT Line Scan with SLO Image of the LE Showing the Defect in the IS/OS Junction with Intact ELM and RPE Layer at the Site of IS/OS Defect.

Discussion

An arc welding unit emits both infra and ultraviolet lights and the retinal damage occurs when the defence mechanisms are overwhelmed by prolonged exposure.1 Normally, the cornea absorbs the UV radiation below 300 nm, and the crystalline lens absorbs light from 300 to 400 nm, thus protecting the retina from its damaging effects.1 However, a small fraction of UV-B radiation between 300 to 310 nm may penetrate the cornea and lens to reach the retina.1 The damage to the retina from welding arc units comes from the visible light especially the 400 to 440 nm and from the potential 300 to 310 nm ‘window’ which may penetrate the cornea and crystalline lens.1

Previous publications have used the Stratus OCT to describe the structural changes at the fovea in welder’s maculopathy. Lucas et al. and Vedantham et al., have described it as disruption of the inner high reflective layer (HRL) corresponding to the outer neurosensory retina, and Huang et al., described it as a small outer lamellar cystic change.2,4,5 However, with the advent of the higher resolution OCT imaging, we are now able to better visualize and stratify the outer retinal layers. We found that, the faceted lesion at the fovea seen on fundus biomicroscopy, corresponded with a distinct area of disruption of the IS/OS junction on FD OCT scans. In all the line scans, the ELM and RPE layer remained intact at the site of IS/OS defect. The IS/OS junction represents the boundary between the photoreceptor IS and the OS and the ELM represents the border between the outermost aspect of the outer nuclear layer and the photoreceptor IS myoid portion.6 Our FD OCT findings suggest that the changes in welder’s maculopathy were confined to the photoreceptor IS/OS junction and the histological finding by Hope–Ross et al., on solar retinopathy have shown that the changes were confined to the photoreceptor OS, seen as vesiculation and fragmentation of the photoreceptor lamellae and the presence of discrete whorls within the disc membranes.7 They also speculated that the foveal photoreceptor OS membranes appeared more susceptible to damage than any other cell component.7 Wakabayashi et al. and associates, in their recent article on foveal microstructure after retinal detachment repair, have speculated that the intact ELM with disrupted IS/OS junction would presumably indicate that changes are limited to the IS/OS junction and don’t extend to the photoreceptor cell bodies.6 This may mimic situation in eyes with welder’s maculopathy.

All our patients were young males, involved in shielded metal arc welding and did confirm that they were wearing protective eye wear while at work. Arend et al. had noted the occurrence of welder’s maculopathy despite wearing protective lenses and speculated that the retinal damage had resulted from use of inadequate filters.8 The present case series also points to the similar occurrence of retinal damage, despite wearing protective glasses. And as mentioned in their article, the lack of corneal involvement in our patients supports the use of protective eye wear. However, one of our patients did confirm that in order to perform high precision welding, they would flip the protective glass away for a very short time. A similar observation was also made by Ake Sanden9, he had observed that most welders could not see well enough with the mask on, to strike the arc they would flip up, and then flip it down again once the arc was going and this exposed their unprotected eyes to the intense light for a while. It is difficult to ascertain in our series, whether the retinal damage occurred due to inadequate filters or due to inadequate wear, though both could have played a role. We think that the diagnosis of CSC in the first case report was a new diagnosis over his existing foveal lesion and not related to welder’s maculopathy. Foveal lesion was appreciable after the subretinal fluid got absorbed. Our second patient illustrates the fact that the IOL did transmit phototoxic light to damage the retina, and reiterates the need for choosing appropriate IOL with UV and blue light absorbing properties, in occupationally demanding situations.

In conclusion, FD OCT imaging in welder’s maculopathy shows a microstructural damage involving the IS/OS junction of the photoreceptors, corresponding to the faceted lesion seen at the fovea clinically. It offers a non-invasive way of evaluating the foveal damage in cases of welder’s maculopathy.

References

  1. Mainster Ma, Turner PL. Retinal injuries from light: Mechanisms, Hazards and Prevention. In Ryan SJ, Hinton DR, Schachat AP, Wilkinson P, eds. Retina. 4th Ed, vol 2. Mosby Elsevier Publishers; 2006.
  2. Huang SJ, Gross NE, Costa DL, Yannuzzi LA. Optical coherence tomography findings in photic maculopathy. Retina. 2003;23: 863–866 doi:10.1097/00006982-200312000-00020 [CrossRef]
  3. Gass JDM. Photic Maculopathy. In: Gass JDM, ed. Stereoscopic Atlas of Macular Diseases; Diagnosis and Treatment, 4th edition, vol 2. Mosby Publishers; 1997:760–769.
  4. Lucas RS, Harper CA, McCombe MF, Mainster MA, Sliney DH, Zamir E. Optical coherence tomography findings in welder’s maculopathy. Retinal cases & brief reports. 2007; 1: 169–171. doi:10.1097/01.ICB.0000279652.22196.70 [CrossRef]
  5. Vedantahm V. Optical coherence tomography findings in a case of chronic welder’s maculopathy. Eye. 2006; 20: 269–271. doi:10.1038/sj.eye.6701846 [CrossRef]
  6. Wakabayashi T, Oshima Y, Fujimoto H, et al. Foveal microstructure and visual acuity after retinal detachment repair. Ophthalmology. 2009Mar; 116(3):519–528. doi:10.1016/j.ophtha.2008.10.001 [CrossRef]
  7. Hope-Ross MW, Mahon GJ, Gardiner TA, Archer DB. Ultrastructural findings in solar retinopoathy. Eye. 1993; 7 (Pt 1): 29–33.
  8. Arend O, Aral H, Reim M, Wenzel M. Welders maculopathy despite using protective lenses. Retina. 1996; 16(3): 257–259. doi:10.1097/00006982-199616030-00014 [CrossRef]
  9. http://en.wikipedia.org/wiki/Arc_welding
Authors

From the Pushpagiri Vitreo-Retina Institute (SP, MO, VK), Secunderabad, India; and University of California (SP), Davis, Sacramento, California.

The authors have no financial or proprietary interest in the materials presented herein.

Address correspondence to Dr. Suman Pilli, Ophthalmology Department, 4860 Y Street, Suite 2400, Sacramento, CA-95817. E--mail: sumandoc2000@yahoo.com

10.3928/15428877-20100215-93

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