Dr. Priyansha Chatterjee, C18819, Dr.Padmamalini Mahendradas, Dr. Shetty hujang K, Dr. Rohit Shetty, Dr. Ankush Kawali
INTRODUCTION: In the clinic, a meticulous iris examination is of utmost importance while performing an initial undilated anterior segment examination, which gives us indispensable, subtle clues and on several occasions, clinches the diagnosis in a number of ophthalmic diseases. Starting from various iris nodules in uveitis conditions, iris masses and granulomas in endopthalmitis to altered iris patterns in Fuchs’ heterochromic iridocyclitis and viral anterior uveitis and several such others, have prominent iris changes. Iris derives its color from melanin pigments in the stroma and the distribution of these pigments is altered in various diseases, which is readily picked up as iris heterocromia and loss of iris stroma seen as atrophy.
Iris autofluorescence originates from the melanin pigment in iris stromal layer. Recent studies were done to obtain autofluorescence images by near infrared laser. Recently Liu et al studied the iris autofluorescence pattern in Fuchs’ heterochromic iridocyclitis and suggested that it was a promising, objective method of diagnosing FHIC.
AIM: To study the near infrared iris AF patterns in eyes diagnosed with uveitis due to various etiologies.
MATERIALS AND METHODS:This study was conducted in the department of Uvea and ImmunologyServices, Narayana Nethralaya, 121/C, Chord Road, Rajajinagar, 1st R Block, Bangalore – 560 010.It is a Prospective, Cross Sectional Study.The study has been approved by the Institutional Research and Ethics Committee of Narayana Nethralaya Postgraduate Institute of Ophthalmology, India and was conducted in accordance with the tenets of the Declaration of Helsinki. A written informed consent was obtained from all patients before the procedure.
Twenty eyes of ten patients who were diagnosed with uveitis in our clinic were included. Eyes with clear media where good quality imaging was possible were included. All patients underwent anterior segment color imaging with slit lamp (TOPCON DC-3, Topcon Medical Systems, Inc., Oakland, NJ). Iris Autofluorescence (AF) images were obtained using a confocal scanning laser ophthalmoscope CSLO (Heidelberg Retina Angiograph 2, HRA2). The excitation wavelength of 795nm was applied for near infrared laser imaging. All images were taken by a single user.
RESULTS: Ten subjects were included in the study out of which 4 were females and the rest were males. The mean age group of the study sample was 40.2 +/- 16.5 years. Three of them had bilateral involvement while the rest had unilateral disease. Only two patients with granulomas were pseudophakic, the rest were phakic.
Autofluorescence in normal iris showed uniform moderate intensity hyper autofluorescence at the pupillary ruff, pupillary zone and collarette crests with mild hyper autofluorescence at the ciliary zone with hypo autofluorescentradial regions. Viral and post traumatic anterior uveitis showed normal iris pattern in the pupillary border and pupillary zone, the collarette region showed mild hyper autofluorescence with loss of distinction of the crest and radial slits, ciliary zone showed mild hyper autofluorescence with loss of the radial regions.
Autofluorescence pattern in iris granulomas(fungal or chronic endophthalmitis) showed intense hypo autofluorescent lesions with fuzzy border which gradually disappeared on serial follow up as the disease resolved with treatment.Autofluorescence pattern in Fuch’s heterochromic iridocyclitis was noted in two patients, with unilateral disease. A characteristic petaloid pattern with moderate hyper autofluorescence was seen in the pupillary zone in both eyes, moderately intense hyper autofluorescence with reticular pattern was seen in the collarette and ciliary zone with loss of radial hypo autofluorescence pattern seen normally in the ciliary zone.The other unaffected eye showed a normal iris autofluorescence pattern. Heterochromia was barely detected in these eyes on iris color photograph.
DISCUSSION: Iris autofluorescence pattern noted in our study revealed certain characteristic patterns in conditions like BAIT, FHIC and iris granulomas and nodules which can be used as an adjunct diagnostic tool as well as a prognostic tool to monitor these generally chronic conditions. In Fuchs’ Heterochromic iridocyclitis, iris autofluorescence revealed characteristic changes when clinically no evident iris heterochromia was detected. Studies have also reported that iris autofluorescence can be used for early detection of FHIC in the other eye in a bilateral condition before the appearance of clinical signs. The IAF pattern in Bilateral acute iris transillumination reflects the nature of the disease and may prove to be a confirmatory evidence in cases of diagnostic dilemma. The strength of this study is that majority of the study subjects (seven) were pseudophakic, thus there were no bias because of expected iris pigmentation changes post cataract surgery.
However, the limitations of this study is the small sample size without which this tool cannot be standardized. The study also lacked long term follow up to document iris changes.
Conclusion:Characteristic AF patterns appeared in eyes with uveitis showing iris depigmentation. Near-infrared AF is a promising, objective diagnostic and prognostic technique in FHIC and other uveitis conditions. To the best of our knowledge this is the first study on uveitic conditions using infrared iris AF.
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