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FREQUENCY OF DIABETIC RETINOPATHY IN A TERTIARY CARE HOSPITAL USING DIGITAL RETINAL IMAGING TECHNOLOGY.

Byline: Azizul Hasan Aamir and Sanaullah Jan

ABSTRACT

Objective: The objective of this study was to determine the frequency of diabetic retinopathy in a tertiary care hospital using digital retinal imaging technology.

Methodology: This descriptive study was carried out in the department of Diabetes, Endocrinology and Metabolic Diseases, Hayatabad medical complex Peshawar. Patients referred from outpatient department, general practitioners and from private clinics were included and after taking their basic demographic data were referred to the department of Diabetes for Fundus Photograph using Canon CR1 non-my driatic digital retinal camera. Photographs were analyzed first by Endocrinologist and later by an Ophthalmologist to assess the severity of retinopathy.

Results: Two thousand one hundred and twenty three patients with type 2 diabetes were evaluated clinically followed by fundus photography by retinal digital imaging The frequency retinopathy and maculopathy was 32.03 % and 6.31 % respectively (both retinopathy and maculopathy 38.34%).

Three seventy four patients (17.6% patients) received laser treatment for prevention of blindness. Conclusion: Screening for Diabetic retinopathy using digital camera is a useful technique and detects DR effectively in diabetic patients in a tertiary care setting. This technique is useful in mass screening and can detect, reduce and prevent blindness due to diabetes in our population.

Keywords: diabetic retinopathy, digital retinal imaging, diabetic retinopathy severity scales.

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This article may be cited as: Aamir AH, Jan S. Digital Retinal Imaging Technology. J Postgrad Med Inst 2012; 26(1): 29-33. Frequency of Diabetic Retinopathy in a Tertiary Care Hospital Using

INTRODUCTION

As more and more people are being affected with diabetes and with poor metabolic control, treating physicians, diabetologist and ophthalmologists are seeing diabetics with multiple complications. Diabetic Retinopathy is the commonest complication of diabetes mellitus and is the earliest manifestation of the micro vascular complications of diabetes mellitus'.

In the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR), a large population based study in 10 countries in southern Wisconsin, USA, the prevalence of any retinopathy in those with onset of diabetes after the age of 30 years (mostly with Type 2 DM) is 29% those within 5 years of diagnosis and 78% in those with diabetes duration more than 15 years2. Diabetic retinopathy is the commonest cause of blindness in the working age population in the developed countries.

It's now accepted that early detection of retinopathy and subsequent treatment with laser reduces the incidence of blindness due to diabetes, if screening is done in the community3' `~. Diabetic retinopathy fulfils all the criteria for a screening program. It occurs as a continuum, where in the early subclinical stages, changes in the retina can only be demonstrated by the use of fluoresce in angiography, to the stages whereby ophthalmologic examination reveals retinopathy but the visual acuity is still unaffected, to the final stages whereby severe visual impairment and blindness to a computer for storage and subsequent retrieval and analysis.

The fundus photographs were carefully analyzed by both authors. The retinal abnormalities were classified according to the International Clinical Diabetic Retinopathy Disease Severity Scale (Table 1) and the International Clinical Diabetic Macular Edema Disease Severity Scale (Table2) produced by the International Council of Ophthalmology6. Any patient requiring further input from Ophthalmologist were referred to Ophthalmology department where further investigation like detailed eye examination and Angiography were done and Laser treatment if required was offered.

RESULTS

A total of 2123 diabetic patients were seen during the study period and fulfilled the selection criteria. The mean age was 57.4 (SD22) years. Most of the respondents were Pakistani (86%), the rest were Afghan refugees (9.5%) and Afghan nationals (4.5%). Forty nine percent of them were males.

The duration of their diabetes was : less than 1 year 16%, 1-5 years 32% 5-9years 24% and greater than 10 years 28 %. Concomitant hypertension was present in 54.1%. One-quarter of them had ever been seen by an ophthalmologist. These include the subjects consulting the ophthalmologist for disease other than diabetes, for treatment of cataracts and for screening purpose. Cataracts were present in 2% of the patients studied. Very few patients (9%) ever received laser photocoagulation for their retinopathy prior to screening. Sixteen percent of the patients in the study had visual acuity of 6/12 or worse in the better eye.

Mydriatic eye drops were used in 16% of the patients studied. Retinal photographs of fourteen patients were unreadable. Six hundred and eighty patients (32.03%) were found to have retinopathy. The severity of retinopathy (based on the International Clinical Diabetic Retinopathy Disease Severity Scale) was as follows: mild non- proliferative 59.3%, moderate non-proliferative 18.7%, severe non- proliferative 14.8 %, proliferative 6.4%.

The prevalence of maculopathy was 6.31% (based on International Clinical Diabetic Macular Edema Disease Severity Scale): mild (hard exudates the away from the macula) 42.7%, moderate (hard exudates within the macula but not involving the fovea) 37.3%, and severe (hard exudates encroaching upon the centre of the macula) 19.9 %. Overall, 38.34% of these diabetic patients had either retinopathy or maculopathy Sight threatening eye disease (STED), defined as moderate non-proliferative diabetic retinopathy or

Table 1: International Clinical Diabetic Retinopathy (DR) Disease Severity Scale

Proposed disease severity Level###Finding observable with dilated ophthalmoscopes

No apparent DR###No abnormalities

Mild non-proliferative DR###Micro aneurysms only

Moderate non-proliferative DR###More than "mild" but less than "severe"

Table 2: International Clinical Diabetic Macular Edema (DME) Disease Severity Scale

Proposed disease severity level###Findings on dilated opthatmoscopy

DME absent###No retinal thickening or hard exudates present in posterior pole

DME Present###Some retinal thickening or hard exudates present in posterior pole

If DME is present, it can be

categorised as follows:

Mild DME###Some retinal thickening or hard exudates present in posterior pole but distant

###from the centre of the Macula

Moderate DME###Retinal thickening or hard exudates approaching the centre of the macula but

###not involving the centre

Severe DME###Retinal thickening or hard exudates involving the centre of the macula

worse, circinate maculopathy and hard exudates within 1 disc diameter from the centre of the fovea) occurred in l89cases (8.9%) and included some mild cases of NPDR as well. Three seventy four patients (17.6% patients) received laser treatment to prevent deterioration of vision.

Among these diabetic patients with concomitant hypertension, retinopathy was detected in (3 8.8%). Amongst total number of patients (518)28% of patients had diabetes for more than 10 years.

DISCUSSION

Our study demonstrated overall retinopathy present in diabetics to be 32.03%. Comparing this to other national studies where it was found to be 22%~' 8 but difference of this higher percentage of patients could be explained due to patients in present study were in specialized

Diabetes unit and hence higher percentage of complication is expected. The new international grading system used in the study is a more evidence-based approach to the classification of the disease and it incorporates data found in excellent trials such as the ETDRS and the WESDR. The main classification looks at the visible vascular events from the earliest change (i.e. micro aneurysms) to the blot haemorrhages, venous beading, intra-retinal micro vascular abnormalities (IRMA) and finally the advance pre- retinal and vitreous haemorrhges. The second part looks at the problem of exudative maculopathy which consist of macular hard exudates and macular oedema. It should be noted that macular oedema can only be appreciated if the digital imaging system has stereoscopic capabilities. However, the best method for looking at retinal thickening is still by indirect ophthalmoscopy or slit-lamp biomicroscopy.

It is important also to note that any stage of diabetic retinopathy can be associated with diabetic macular oedema based on the findings of hard exudates. We realize that the c classification was based on "dilated ophthalmos- copy" but our retinal photography was taken through the undilated pupils (in most patients). Since the camera we used was able to capture a clear central view of the fundus in the majority of cases, we think further dilatation of the pupils may not be necessary in most cases. Generally speaking, we find that the classification has assisted us in the early referral of STED to the specialists.

Present study was done in hospital setting, but previously study done has shown that technique using single-image retinal photographs taken with a nonmydriatic retinal camera in primary care offices, with primary care clinicians reading the resulting images, may be a cost- effective way to help reduce vision loss in diabetic patients who have limited access to specialize care The prevalence of diabetic retinopathy in our community is predictably high7'8. Early identification and treatment of diabetic retinopathy through screening is a cost effective strategy for improved health care in diabetic populations'deg. Previous study done in the same department showed low awareness of DR in the patients and it was suggested that mass screening programs using digital camera technologies may be used to detect Diabetic Retinopathy early and also large number of patients can be screened in a shorter duration'.

Digital retinal imaging has offered a new range of imaging possibilities and effective way to help reduce vision loss in diabetic patients who have limited access to ophthalmologists. This study has its limitations as it was not a community based population study and the observations were conducted in a tertiary care setting. Also the patients referred were representing a wider population and hence looking at the observations of our study a larger community based study will help us get the real prevalence of DR in our set up. On a positive note this screening programe and collaboration of Ophthalmology and endocrinology department has been able to save potentially (680 X 5) 3400 blind years within span of 6 months time. Similar linkages and referral with other departments will save millions of people from blindness.

CONCLUSION

Screening for Diabetic retinopathy using digital camera is a useful technique and detects DR more effectively in diabetic patients in a tertiary care setting.

This technique is useful in mass screening and can detect, reduce and prevent blindness due to diabetes in our population. Grant Support, Financial Disclosure and Conflict of Interest Canon CR! Camera used in the study was donated by Fred Hollows Foundation (FHF) Australia for screening purposes only.

REFERENCES

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2. Klein R, Klein BE, Moss SE, Davis MD, DeMets DL. The Wisconsin epdimiologic study of diabetic retinopathy. III. Prevalence and risk of diabetic retinopathy when age at diagnosis is 30 or more years. Arch Opthalmol 1984; 102:527-32.

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9. Farley TF, Mandava N, Prall FR, Carsky C. Accuracy of Primary Care Clinicians in Screening for Diabetic Retinopathy Using Single-Image Retinal Photography. Ann Fam Med 2008; 6:428-34.

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Author:Aamir, Azizul Hasan; Jan, Sanaullah
Publication:Journal of Postgraduate Medical Institute
Article Type:Report
Geographic Code:9PAKI
Date:Mar 31, 2012
Words:2056
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