1

Fundus Autofluorescence (FAF) in the Diagnosis of GlaucomaZeinab El Sanabary, M.D.

Professor of Ophthalmology, Cairo University, Egypt

Progressive chorioretinal atrophy is seen in glaucoma in the parapapillary region. Zone beta is an area of visible sclera and large choroidal vessels, adjacent to the optic disc border. Zone alpha is a more peripheral area of irregular hypo- and hyper-pigmentation. This classification into β- and α-parapapillary atrophy (β-PPA and α-PPA) has now been accepted to have an association with glaucoma (1).

β-PPA atrophy has been reported to be associated with both the prevalence and progression of open-angle glaucoma (OAG). The presence of β-PPA and its enlargement over time have been reported to precede and predict the onset of glaucoma in ocular hypertensive eyes. Progression of β-PPA (α-PPA turns into β-PPA) is correlated with progression of the morphologic glaucomatous damage and visual field loss (2).

IntroductionFAF is caused by the lipofuscin of RPE cells which derives primarily from incomplete digestion of rod outer segment discs. FAF allows visualization of metabolic changes at the level of the RPE and identification of areas at high risk for development of functional loss.

Fig (1) Colored photo showing α and β parapapillary zone 1

PurposeTo assess the role of fundus auto fluorescence (FAF) in detection of parapapillary atrophy as a biomarker for glaucoma diagnosis and progression.

Introduction• Eyes with retinal disease were excluded from the study• Modified Topcon digital fundus camera using an exciter filter of wavelength range of 535-585 nm and a barrier filter of 605-715 nm was used.• Colored fundus images (50°) and FAF of the optic disc in all studied eyes were obtained and correlated to field (Humphrey) and OCT (Optovue or Cirrus Zeiss) changes for glaucoma

Methods• Uncontrolled cross-sectional prospective analysis of 30 cases referred for automated perimetry and OCT to confirm or exclude diagnosis of glaucoma were included.

Results Autofluorescent areas were detected at the edges of α-PPA in 4 cases out of 7 cases with OHT and in cases of OAG with significant affection of Ganglion Cell Complex or atrophy of RNFL thickness in OCT, even when there are early field defects (12 cases) (Figure 4 & 5). No autofluorescent areas were detected in the 11 cases referred as glaucoma suspect that correlated with the normal OCT findings in 4 of them (Figure 6) while the other 7 cases showed early OCT changes giving a negative correlation with FAF.

Discussion and ConclusionsIn this limited series, autofluorescent areas at the edges of the parapapillary atrophic zone were detected in some cases of ocular hypertension (OHT) and in all cases of open angle glaucoma (OAG) . The negative correlation found in cases of glaucoma suspects was limited to early cases and need larger series to confirm its role. Viestenz et al., 2003 investigated FAF in different stages of glaucomatous optic disc atrophy and found a correlation between the circular extension of autofluorescent area in the parapapillary region and the stage of optic disc atrophy. They also detected larger areas in OHT than normals (3). Laemmer, et al. , 2007 detected also increased autoflourescence in patients with OHT (4).

Viestenz et al, 2006 reported a correlation between the extent of autofluorescent parapapillary atrophy and the stages of glaucomatous optic nerve head atrophy with no significant difference between the types of glaucoma whether OAG, normotensive glaucoma (NTG) or pseudoexfoliation glaucoma (PSXG) (5).

In conclusion, parapapillary autofluorescence (PAF) analysis, being a non invasive objective imaging modality, may provide an indicator and biomarker for predicting development of glaucoma and progression.

1.Jonas, JB. Clinical implications of peripapillary atrophy in glaucoma. Curr Opin Ophthalmol 2005; 16:84-88

2.Rockwood, EJ & Anderson, DR: Acquired peripapillary changes & progression in glaucoma. Graefe’s Arch.Clin. Exp Ophthalmol. 1988; 226:510.

3.Viestenz A, Mardin CY, Langenbucher A, Naumann GO: In-vivo measurement of autofluorescence in the parapapillary atrophic zone of optic discs with and without glaucomatous atrophy. Klin Monbl Augenheilkd 2003; 220 :545-550

4.Laemmer, R, Horn, FK , Viestenz, A et al: Measurement of autofluorescence in the parapapillary atrophic zone in patients with ocular hypertension. Graefe’s Arch Clin Exp Ophthalmol 2007; 245:51–58

5.Viestenz , A, Langenbucher, A , Mardin, CY: Parapapillary autofluorescence as indicator for glaucoma. Klin Monbl Augenheilkd 2006; 223:315-320

Figure (6): Colored photo of both eyes of a female aged 42y showing significant cupping with pallor & left nasal shift of vessels (glaucoma suspect). However the field is normal and No detectable changes in the OCT scan of RNFL . The FAF is matching these findings with no evidence of autofluorescence of α- PPA zone. β-PPA zone is not detected either.

Figure (5): Colored fundus of a female patient (40y) showing significant optic disc cupping & atrophic neuro-retinal rim (OAG). The field showed nasal stepping. The α-PPA zone is autofluorescent

Figure (4): A case of OAG (67y) showing significant GCC atrophy, early field defects & auto-fluorescent α- PPA

References

7

12

11

OHTOAGGlaucoma Suspect

02468

101214

OHT OAG Gl. suspect

FAFNo FAFOCT/Field changes

Figure (3): Detection of FAF in different glaucoma stages in the study

Figure (2): Distribution of cases