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ORIGINAL ARTICLE
Year : 2017  |  Volume : 30  |  Issue : 2  |  Page : 480-484

Optical coherence tomography and fundus autofluorescence findings in areas of geographic atrophy owing to age-related macular degeneration


1 Ophthalmology Department, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Ophthalmology, Mansoura University, Mansoura, Egypt

Date of Submission16-Mar-2016
Date of Acceptance01-Aug-2016
Date of Web Publication25-Sep-2017

Correspondence Address:
Sally A Mohamed Elnaghy
Dakahlia, El-Mansoura, 35511
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_116_16

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  Abstract 

Objective
To evaluate the optical coherence tomography(OCT) and fundus autofluorescence(FAF) findings in cases of geographic atrophy owing to age-related macular degeneration(AMD).
Background
Old patients who have dry-typeAMD were included.
Patients and methods
This study was conducted on 30 eyes to assess OCT and FAF findings in cases of geographic atrophy owing to AMD.
Results
The study provedthrough OCT findings that retinal pigment epithelium atrophy was present in all patients(100%). Drusen were present in 28patients(93.3%). Back scatter was present in all patients(100%). Retinal anatomy alteration was present in all patients(100%). Posteriorvitreous detachment was present in nine patients(30%). FAF findings were the margins of geographic atrophy. There was one eye with no areas of increased FAF(3.3%), 18 eyes were diffuse(60%), eight eyes were banded(26.7%), three eyes were focal(10%), and patchy type was not found(0%). In the current study, 14(46.7%) had well-defined edges, whereas 16 eyes(53.3%) had ill-defined edges. Moreover, 15 eyes(50%) were found to have unifocal decreased FAF, whereas15 eyes(50%) were found to have multifocal decreased FAF. In addition, 12 eyes(40%) had irregular shape, whereas 11 eyes(36.7%) had circular shape and seven eyes(23.3%) had oval shape. In the current study, the size of areas of decreased FAF was compared with the optic disc diameter of the same affected eye, and this area ranged from 0.5 to 4 disc diameters, with a median of 2.31±0.96 disc diameters.
Conclusion
OCT and FAF are complementary in identifying, examining, and managing geographic atrophy owing to AMD. The advantages of OCT over FAF are that it allows quantitative and qualitative analysis of geographic atrophy lesions, allowing better structural identification of the lesion.

Keywords: age-related macular degeneration, fundus autofluorescence, geographic atrophy, optical coherence tomography


How to cite this article:
Kamel El-Sobky HM, Badawi NM, Mohamed Elnaghy SA. Optical coherence tomography and fundus autofluorescence findings in areas of geographic atrophy owing to age-related macular degeneration. Menoufia Med J 2017;30:480-4

How to cite this URL:
Kamel El-Sobky HM, Badawi NM, Mohamed Elnaghy SA. Optical coherence tomography and fundus autofluorescence findings in areas of geographic atrophy owing to age-related macular degeneration. Menoufia Med J [serial online] 2017 [cited 2019 Apr 18];30:480-4. Available from: http://www.mmj.eg.net/text.asp?2017/30/2/480/215432


  Introduction Top


Age-related macular degeneration(AMD) is the leading cause of severe visual impairment in elderly people in industrialized countries[1],[2]. In the past decade, notable progress in our comprehension of geographic atrophy(GA) has been made, particularly the discovery of susceptibility genes that point to the involvement of chronic inflammation at the earliest stages of the disease[3].

GA is responsible for∼20% of legal blindness attributable to AMD and will become even more prevalent with the growth of the elderly population[4]. The pathophysiologic mechanism of retinal pigment epithelium(RPE) cell atrophy with corresponding atrophy of the choriocapillaris and outer neurosensory retinal layers in this disorder still remains unclear. Several lines of experimental and clinical evidence indicate that lipofuscin accumulation in the lysosomal compartment of RPE cells plays a critical role in the disease process[5].


  Patients and Methods Top


This study was conducted on 30 eyes(11males and 19females), with mean age of 71.86±9.89years, to assess optical coherence tomography(OCT) and fundus autofluorescence(FAF) findings in cases of GA owing to AMD.

Inclusion criteria

The following inclusion criteria were applied:

  • GA owing to AMD
  • Individuals older than 50years.


Exclusion criteria

The exclusion criteria included the following:

  • History of retinal surgery
  • History of laser treatment
  • History of retinal vascular occlusion
  • History of diabetic retinopathy
  • History of GA owing to hereditary macular dystrophy
  • Active neovascular AMD.


Methods

All patients underwent the following:

  • Visual acuity measurement using Snellen chart
  • Manifest refraction using the autorefractometer
  • Evaluation of the best corrected visual acuity
  • Slit lamp biomicroscopy to examine the anterior segment of the eye and the pupil and noting any abnormalities
  • Intraocular pressure measurement
  • Amsler grid test
  • Fundus examination: dilated fundus examination by indirect ophthalmoscope and Volk (Volk Optical Inc., Mentor, OH) 90D Lens
  • Fundus colored photography
  • OCT
  • FAF imaging.


Then the data were collected for evaluation and analysis of the changes in GA owing to AMD.


  Results Top


Demographic data

The study was conducted on 30 eyes from 25patients, aged 50years or older, with all having atrophic type of AMD. They were chosen according to the inclusion criteria mentioned before.

The ages of patients ranged from 54 to 87years, with a mean of 71.86±9.89[Table1]. Overall, 19patients were females(63.3%) and 11patients were males(36.7%). The female: male ratio among studied patients was 1.72:1[Table2].
Table 1: Age distribution among the studied group

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Table 2: Gender distribution among the studied group

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OCT findings[Table3] and [Figure1] and [Figure2] revealed the following:
Table 3: Optical coherence tomography findings among the studied group

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Figure 1: Optical coherence tomography findings.

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Figure 2: Spectral optical coherence tomography image showing posterior vitreous detachment, atrophic outer retina, thin retinal pigment epithelium, and increased choroidal transmission.

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  • RPE atrophy was present in all patients(100%)
  • Drusen was present in 28patients(93.3%)
  • Back scatter was present in all patients(100%)
  • Retinal anatomy alteration was present in all patients(100%)
  • Posterior vitreous detachment(PVD) was present in nine patients(30%).


Fundus autofluorescence

Areas of increased FAF at the margins of GA were classified according to FAM study into diffuse, banded, focal, patchy, and none.

There was one eye with no areas of increased FAF(3.3%), 18 eyes were diffuse(60%), eight eyes were banded(26.7%), three eyes were focal(10%), and patchy type was not found(0%)[Table4].
Table 4: Fundus autofluorescence findings among the studied group

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Areas of decreased FAF were classified as follows[Table4]:

Edges

In the current study, 14 eyes(46.7%) had well-defined edges[Figure3], whereas 16 eyes(53.3%) had ill-defined edges[Figure4].
Figure 3: Fundus autofluorescence (FAF) image showing well-defined edge at areas of decreased FAF.

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Figure 4: Fundus autofluorescence (FAF) image showing ill-defined edge at areas of decreased FAF.

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Number

A total of 15 eyes(50%) were found to have unifocal decreased FAF[Figure5], whereas 15 eyes(50%) were found to have multifocal decreased FAF[Figure6].
Figure 5: Fundus autofluorescence (FAF) image showing unifocal area of decreased FAF.

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Figure 6: Fundus autofluorescence (FAF) image showing multifocal areas of decreased FAF.

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Shape

Overall, 12 eyes(40%) had irregular shape, whereas 11 eyes(36.7%) had circular shape and seven eyes(23.3%) had oval shape.

Size

In the current study, the size of areas of decreased FAF was compared with the optic disc diameter of the same affected eye, and this area ranged from 0.5 to 4 disc diameters with a median of 2.31±0.96 disc diameters[Table4].


  Discussion Top


GA is defined as any sharply delineated round or oval area of hypopigmentation or depigmentation or apparent absence of the RPE, in which choroidal vessels are more visible than in the surrounding areas and which must be at least 175 μm in diameter[6].

In the present study, eyes with GA measuring 500 μm(0.5mm) or more in the greatest linear diameter were studied, as was done in the recent years by other study groups[7].

Spectral OCT and FAF images reviewed in the study were obtained using the Spectralis HRA/OCT(Heidelberg Retinal Angiograph; Heidelberg Engineering, Heidelberg, Germany).

The OCT machine combines high-resolution spectral domain OCT with an SLO. The system allows for simultaneous OCT scans with FAF imaging, making it easier to find small changes in FAF and analyze them on OCT[8]. The instrument uses an 870-nm broadband super luminescent diode laser for the OCT channel. FAF is done without needing any dye. The OCT machine offers BluePeak blue laser autofluorescence technology. FAF takes the advantage of the fluorescent properties of lipofuscin, a key component of RPE metabolism. The characteristic patterns of autofluorescence can noninvasively reveal the extent of GA.

The aim of the work is to study the changes in the retinal layers near atrophic lesions in patients with GA secondary to AMD.

This study was done on 30 eyes of patients aged from 54 to 87years, all having atrophic type of AMD.

Inclusion criteria included clear media to allow FAF imaging and a total area of GA larger than 0.5 mm 2. Exclusion criteria included eyes with any history of atrophy of RPE secondary to wet type of AMD, hereditary retinal diseases, laser photocoagulation(especially grid laser treatment), pathological myopia, retinal detachment, ocular trauma, and vitreoretinal surgeries.

Each patient had a detailed ophthalmological examination with best corrected visual acuity using logMAR chart, AF of the posterior pole using spectralis HRA/OCT, and OCT scanning at areas of GA using spectralis HRA/OCT.

In the present study, the ages of patients ranged from 54 to 87years, with a mean of 71.86±9.89years. Atotal of 19patients were females and 11patients were males. The female to male ratio among studied patients was 1.72:1.

Men tend to have higher prevalence rates than women in the younger age groups(<80years), whereas GA is more frequent in women than men in the older age group(≥80years), and this was in agreement with a meta-analysis performed in 2004 by Freidman etal.[4].

In the present study, regarding OCT findings near atrophic lesions, th e inner retinal layers were normal, whereas the outer retinal layers showed severe structural alteration in all eyes characterized by a complete loss of defined boundaries between the layers. An increased optical reflectivity from the choroid owing to increased penetration of the light through the atrophic RPE was also observed in all GA areas. Drusen was present in 93.3% of cases.

In the present study, PVD was detected in 30% of cases, but we did not find any vitreomacular traction(VMT). Studies employing echography and OCT to study the vitreoretinal interface have reported a high coincidence of persistent macular vitreoretinal adhesion and AMD, particularly in the setting of exudative(wet) AMD[9],[10]. For example, Robinson etal. [11] retrospectively analyzed 29patients with active wet AMD in one eye and dry AMD in the fellow eye with ultrasound and OCT[11],[12],[13]. The incidence of PVD by echography was 21% in the eyes with wet AMD, compared with 69% in the eyes with dry AMD(P=0.002). Additionally, vitreomacular adhesion as detected by OCT was present in 38% in eyes with wet AMD and in only 10% in eyes with dry AMD(P=0.008).

In the present study, areas of decreased FAF were classified by the examiner according to their edges, number, shape, and size as mentioned before. Regarding their edges, 14 eyes(46.7%) had well-defined edges, whereas16 eyes(53.3%) had ill-defined edges. Regarding their number, 15 eyes(50%) were found to have unifocal decreased FAF, whereas 15 eyes(50%) were found to have multifocal decreased FAF. Regarding their shape, 12 eyes(40%) had irregular shape, whereas11 eyes(36.7%) had circular shape and seven eyes(23.3%) had oval shape. In the current study, the size of areas of decreased FAF was compared with the optic disc diameter of the same affected eye, and this area ranged from 0.5 to 4 disc diameters with a median of 2.31 disc diameters.

We tried to find any statistical correlation between areas of decreased FAF and OCT findings, but there was no statistically significant correlation between the shape of the edge, the number of foci, the shape of areas, and the size of areas of decreased AF and OCT findings(Drusen and PVD).

There was no statistically significant difference between classes of increased FAF and the age and sex of the study cases, with P values of 0.269 and 0.215, respectively.

In the present study, the incidence of PVD in the study cases was 30%. As mentioned before, Robison etal. [11] have found that PVD is more commonly found in eyes with end-stage AMD that exhibit disciform scarring(40%) than in eyes with active exudative AMD(21%). This result suggests that the development of PVD either promotes CNV progression or that macular disciform scarring may facilitate vitreoretinal dehiscence by altering the integrity of the ILM.

Regarding VMT in the present study, there was no VMT, whereas in the study by Robison etal.[11], the incidence of VMT was 10% in eyes with dry AMD and 38% in eyes with wet AMD. This result suggests that the development of VMT is more common with wet AMD. Eyes with wet AMD were excluded from the present study.

Whether VMT is a cause or a result of AMD remains unclear[14]. Local inflammation, scarring, and disruption of the photoreceptor-RPE interface induced by AMD may activate Muller cells and possibly astrocytes, causing focal corresponding vitreous adhesions[15]. These connections induce tractional forces on the retina[15].


  Conclusion Top


OCT and FAF are complementary in identifying, examining, and managing GA due to AMD.

The advantages of OCT over FAF are as follows:

  1. OCT allows quantitative and qualitative analysis of GA lesions, allowing better structural identification of the lesion, especially retinochoroidal anatomy alteration complex, RPE atrophy, Drusens, and associated vitreoretinal interface abnormalities.


The advantages of FAF over OCT are as follows:

  1. FAF was superior in defining edges, number, shape, and size of GA.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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    Figures

  [Figure1], [Figure2], [Figure3], [Figure4], [Figure5], [Figure6]
 
 
    Tables

  [Table1], [Table2], [Table3], [Table4]



 

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