Diabetes mellitus is a disorder in which the blood glucose levels are abnormally high because the body does not produce enough insulin to meet its needs and is a major concern that attains global proportions equally[1]. As per the data submitted by the Global Diabetes Community India has the highest number of diabetics which is also expected to increase in the near future[2]. Diabetic retinopathy, a major complication of diabetes is one of the easily demonstrable example of micro vascular damage that diabetes can inflict in human body which is progressive and caused by the abnormal changes in the retinal vessels. The retinal capillaries and walls becomes progressively degenerated due to increased sugar levels ultimately resulting into the leakage of exudates and grow fragile, brush like branches and scar tissue that can blur or distort the vision images.. Microaneurysms and closure of small vessels may result that loses the ability of red blood cells to be transported to the retina which paves its way to the disruption of the blood retinal barrier[3-4]. Patients with diabetic eye disease do not produce any vital symptoms. Over the course of time the pupils become constricted due to elevated sugar levels. An optimal modality of diagnosis is not yet found out for the early detection of eye disease caused by diabetes. Pupillary dilatation is an essential part for the screening of early diagnosis of diabetic retinopathy[5]. So the purpose of the study was to investigate the effect of pupil dilation (mydriasis) brought about in diabetic and non-diabetic population by three assigned regimens that would provide a better field for practitioners during surgical procedures and field examinations.
MATERIALS AND METHODS
Materials A randomized prospective study was carried out. All patients were recruited from SRM General Hospital and Medical Research Centre, Chennai. The study was approved by the Ethical Committee. The study was conducted over a six month period from July 2010 to December 2010. The selected patients were aged 15 years and above who were diagnosed with diabetes. Non diabetic patients with any secondary illness excluding diabetes were also included in the study. A total of 180 patients were examined with 90 from each group (diabetic and non diabetic). In this study, both the eyes of each patient were analysed. Exclusion criteria included active or previous eye infection or previous ocular surgery.
Methods The patient informed consent was obtained from each subject selected for the study. Age, gender, duration of diabetes, most recent HbA1c value and current sugar levels were recorded. The dilatation of the pupil was the main outcome measure of the study. The treatment regimens were divided into three groups that includes tropicamide 1% two drops in each eye, tropicamide and phenylephrine 0.8% two drops in each eye and tropicamide (1%) and flurbiprofen 0.3% two drops each in each eye. A maximum pupil size of 7mm was the targeted outcome. The diabetic and non diabetic populations were further divided into three individual groups who were assigned with the three different regimens. After the visual acuity testing, the pupil diameter was measured using transparency scale before the instillation of first drop and at every 10 minute intervals after the administration up to one hour. Simultaneously the blood pressure and pulse rates were measured for those who were assigned with regimen 2.
Statistical Analysis SPSS 17.0 was used for the analysis of data. Paired sample t-tests were done to compare the mean dilatation of the pupil among the diabetic and non-diabetic patients. The obtained results of the tests were compared with a standard range of P<0.05.A ‘n’ value of 60 was taken for each individual comparison.
RESULTS
Table 1 shows that tropicamide regimen produced a significant mean dilatation of the pupil for both eyes at P values of 0.042 and 0.036.
Table 2 depicts the results for tropicamide and phenylephrine regimen showing more significant mydriasis at P values of 0.000 and 0.01in diabetic and non-diabetic populations. The tests also showed that the blood pressures and pulse rates which had been monitored were stable between the groups.
Similarly table 3 presents that tropicamide and flurbiprofen regimen produced mean dilatation of the pupil that were profoundly significant at P values of 0.000.
Table 1 Mydriatic Effect of Tropicamide in Diabetic and Non-diabetic patients
Group
Left Eye
Right Eye
Mean
Standard
Deviation
Paired
t-test
Mean
Standard
Deviation
Paired
t-test
Diabetic
5.53
0.730
t = 1.99
P= 0.042
Significant
5.60
0.563
t =2.14
P=0.036
Significant
Non-diabetic
5.67
0.676
5.93
0.640
Table 2 Mydriatic Effect of Tropicamide +Phenylephrine in Diabetic and Non-diabetic Patients
Group
Left Eye
Right Eye
Mean
Standard
Deviation
Paired
t-test
Mean
Standard
Deviation
Paired
t-test
Diabetic
4.97
0.615
t = 5.51
P= 0.000
Significant
4.97
0.850
t =2.68
P=0.01
Significant
Non-diabetic
5.77
0.504
5.50
0.682
Table 3 Mydriatic Effect of tropicamide + Flurbiprofen in Diabetic and Non-diabetic Patients
Group
Left Eye
Right Eye
Mean
Standard
Deviation
Paired
t-test
Mean
Standard
Deviation
Paired
t-test
Diabetic
4.20
0.761
t =9.23
P= 0.000
Significant
4.17
0.531
t =9.97
P=0.000
Significant
Non-diabetic
5.90
0.662
5.83
0.747
DISCUSSION
The pupil dilatation produced by diabetic and non-diabetic population who had been assigned with tropicamide and flurbiprofen regimen produced profoundly significant mydriasis whose results are depicted from the figures provided. As the duration of diabetes increases, the pupil size gets diminished because of the elevated glucose levels. So in order to produce maximum dilatation of the pupil for effective ophthalmological examinations, a combination of tropicamide (muscarinic receptor antagonist) and flurbiprofen (non-steroidal anti-inflammatory drug) is optimal.
Mydriasis is the process of producing dilatation of the pupil when used for various diagnostic tests and ophthalmological therapy[6]. The intensity of mydriasis depends on the pupil sphincter and dilator muscles[7]. Mydriatics are those agents that are used for producing mydriasis and the routinely used are of parasympatholytic and sympathomimetic types. Tropicamide, a parasympatholytic is a rapidly acting mydriatic that blocks the acetylcholine action resulting in relaxation of cholinergically innervated sphincter iris muscles. As a result the adrenergic innervations to the radial muscles will be unopposed and therefore dilatation of the pupil. Flurbiprofen, a non-steroidal anti-inflammatory drug is used to produce dilatation of the pupil via inhibition of the cyclo oxygenase enzyme. The combined formulation of tropicamide with flurbiprofen potentiates its action and ultimately leads to the mydriatic effect.
Monotherapy of tropicamide showed dilatation of the pupil to a less extent when compared to that of the combination. Regular screening for early diabetic retinopathy can be enhanced with the implication of tropicamide and flurbiprofen combination. This also implies that the practitioners dealing with routine screening of early diabetic retinopathy must be significantly packed with profound knowledge about diabetes and the risks that it can cause to the eye so that it can help them to bring an insight to the patients having diabetic eye disease[8]. Also it does provide a good field for ophthalmologic examinations.
Treatment for diabetic retinopathy is only preferred in advanced stages and involves laser treatment, intraocular steroidal injection, cryotherapy and retinal repair depending on the progression of the disease. Strict routine examination of the eye is very crucial and beneficial for the prevention.[9]So the conclusion of the study is that for an effective routine screening of early diabetic retinopathy by dilating the pupils, combination therapy of tropicamide and flurbiprofen can be used.
