Year : 1998 | Volume
: 46 | Issue : 1 | Page : 25--29
Profile of the subtypes of angle closure glaucoma in a tertiary hospital in North India
R Sihota, HC Agarwal
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All Institute of Medical Sciences, New Delhi, India
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All Institute of Medical Sciences, New Delhi
A prospective study of 500 consecutive patients of primary angle closure glaucoma was undertaken to study the clinical profile of the three subtypes: acute, subacute, and chronic. A record of age and sex distributions, symptomatology, the best corrected visual acuity, gonioscopy, visual fields, methods of control of intraocular pressure, and status of the second eye was maintained. Statistical analysis of these parameters and the subtypes of angle closure glaucoma was carried out using the chi-square test. Angle closure glaucoma constituted 45.9% of all primary adult glaucomas seen. 24.8% of these had acute angle closure glaucoma, 31.2% subacute, and 44% chronic glaucoma. Angle closure glaucoma occurred maximally in the sixth decade and females constituted 51.4% of those affected. The difference in symptoms among the subtypes was significant (p<0.001). More than 80% of the chronic eyes had no significant symptoms. Visual field defects specific for glaucoma were seen in only 15.1% of chronic glaucoma eyes. Bilaterality was commonest in subacute angle closure glaucoma (95.5%) and least in acute angle closure 35.5%. Nd YAG iridotomy alone or with topical medication controlled the intraocular pressure in 48.3% of acute angle closure glaucoma, 78.8% of subacutes, and 30% of chronic eyes. Statistically, each parameter reviewed was significantly different among the subtypes. There are considerable differences as well as an overlap of clinical features in the subtypes of angle closure glaucoma, which suggest some anatomical differences or dissimilar pathogenic mechanisms in these eyes.
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Sihota R, Agarwal H C. Profile of the subtypes of angle closure glaucoma in a tertiary hospital in North India.Indian J Ophthalmol 1998;46:25-29
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Sihota R, Agarwal H C. Profile of the subtypes of angle closure glaucoma in a tertiary hospital in North India. Indian J Ophthalmol [serial online] 1998 [cited 2022 Sep 29 ];46:25-29
Available from: https://www.ijo.in/text.asp?1998/46/1/25/14981
Angle closure glaucoma is a protean disease with a differing incidence, indeterminate initial stages, and a varied presentation in difference races. There is a significantly high incidence of angle closure glaucoma (ACG) in India, which forms almost half of all adult primary glaucomas seen., There is however a paucity of literature available about the presentations and relative incidence of the subtypes of angle closure glaucoma.
A prospective study of 500 consecutive patients of primary angle closure glaucoma, routinely referred to the Glaucoma Service of our hospital, was undertaken, to present a profile of the subtypes of angle closure glaucoma.
All patients suspected or diagnosed to have glaucoma in the general out patient department of our hospital are sent for management to the Glaucoma Service. The referrals are based on an individual's symptoms, clinical examination for anterior chamber depth and optic nerve head status, intraocular pressure (IOP) recordings, single or a diurnal variation, a visual field, and occasionally a provocative test. Some cases of acute angle closure glaucoma were initially examined and treated by the ophthalmologist on emergency duty and were then referred to the Glaucoma Service together with their records. There was no standard protocol followed for referral and a prior gonioscopy was only performed in certain cases such as the acute ACGs.
Of the cases referred, 500 consecutive patients diagnosed to have a definitive primary angle closure glaucoma were prospectively studied with respect to the three subtypes of angle closure glaucoma: acute, subacute and chronic as defined by Clemmesen.
(i) Subacute or intermittent ACG: defined as intermittent observed pressure elevations accompanied by prodromal symptoms, headache, haloes, and vision, but with normal tension in the inter paroxysmal period, in patients with an occludable angle.
(ii) Acute ACG: patients with severe attacks of angle closure accompanied by pain and the other usual symptoms.
(iii) Chronic ACG: patients with partially occluded angles and constant IOP elevation. Some patients have no symptoms (creeping ACG), others complain of headache.
We excluded patients in whom no subtypical classification of angle closure glaucoma was possible, for example, suspects, those with aphakia, pseudophakia or previous filtering surgery.
A detailed history and ophthalmic examination of the presenting eye was undertaken. At this point an indentation gonioscopy was performed on each patient by masked observers who did not know the patient's history or decide the patient's final diagnosis. An applanation tonometry, detailed examination of the anterior segment, disc and fundus were recorded. Subacute ACG was diagnosed if there was a significant history, a narrow angle recess with some synechiae or increased pigmentation, a record of raised IOP or a positive dark room prone provocative test. The final diagnosis in all cases was made by only two glaucoma specialists (RS, HCA). If both eyes had the same subtype of ACG, the eye with more advanced optic nerve head changes was reviewed, to prevent observer bias. The patients all underwent a YAG iridotomy in both eyes. Eyes with pressures of more than 21 mmHg were then advised the use of either or both, pilocarpine 2% drops and timolol maleate 0.5% drops to control the intraocular pressure. A diurnal variation or diurnal control of IOP was done 2 weeks after the iridotomy and the gonioscopy was repeated at this time, again by masked observers. If the intraocular pressure was uncontrolled despite topical medications, the patient underwent a trabeculectomy.
The results of surgery at a minimum follow up of three months, were classified as a success if the IOP was <20 mmHg without medication, a qualified success if additional topical medication was required to control the IOP, and a failure if systemic medication or surgery was needed.
Visual fields are known to be altered by alterations in the level of IOP. To allow a comparison of the perimetry among the eyes studied, the visual field was charted with the Goldmann perimeter or the Humphrey visual field analyser, after control of the intraocular pressure medically or post surgery. Two different methods for perimetry had to be employed because the Humphrey perimeter was out of order for almost a year.
Statistical analysis was performed using the chi-square test, overall and between the subtypes.
500 patients diagnosed at our Glaucoma Service to definitively have a primary angle closure glaucoma were included in this study, out of a total of 1,553 patients seen at the clinic. During the same period, there were 588 primary open angle glaucomas (OAG), a ratio of ACG:OAG
In the ACG group as a whole there were 243 (48.6%) males and 257 (51.4%) females. Females predominated in the acute subgroup, 99 of 124 (79.8%), and in the subacute group 104 of 156 (66.7%). Males were more commonly involved in the chronic subtype, 166 of 220 (75.4%). There was no significant difference in the occurence of ACG between males and females in the various age groups [Table:1].
ACG occurred between 30-80 years with the maximally affected decade being the sixth. Analysing the subtypes of ACG vis-a-vis age, by the chi-square test, there was a significant difference in the distribution of subtypes in a comparison between the third and fourth decade (p<0.01) when the acute predominated and between the fourth and fifth decades (p<0.05) when subacute cases were more common [Table:2]. At the older ages, the distribution of the subtypes was not significantly different.
The presenting complaints of the patients are detailed in [Table:3]. Coloured haloes were seen most often by patients having an acute attack (64.5%).
Only 35.3% of those having subacute attacks complained of haloes and 18.2% of patients having chronic angle closure. Ocular pain was most common in the acute and subacute groups, 62.1% and 45.5% respectively. Associated vomiting occurred in 35.5% of acute cases, and 19.9% of the subacutes and was negligible in chronic angle closure. A nonspecific headache and a diminution of vision were commonly encountered in all subtypes of glaucoma. The difference in symptoms among the three subtypes of glaucoma was highly significant (p<0.001). Comparing the occurrence of the symptoms between the sexes, in acute and subacute types this was statistically non-significant, but in the chronic variety the females were more symptomatic (p<0.05).
An absolute eye was most often seen with chronic angle closure glaucoma, 32.3%, and following an acute attack, 15.3%. Ninety absolute eyes were present in the series overall, that is 18%, of which 35 (7%) were bilateral. Only 8.9% of patients who had an acute ACG achieved a vision of 6/12 or better. The best corrected visual acuity was significant different between the subtypes (p<0.001) [Table:4].
Grading the angle of the anterior chamber prior to therapy and without manipulations, by the Shaffer system, the majority of eyes were found to have a closed (0 angle) in acute cases. A closed angle was also seen in 38.2% of chronic ACGs and only 3.2% of subacutes. A slit like opening with no angle structures visible was present in 66% of subacute eyes, 48.6% of chronic ACG eyes, and 41.1% of those having acute ACG. Grade I angles were seen in 23.7% of subacute eyes and 13.2% of those having chronic ACG [Table:5].
There was a highly significant difference between the subtypes (p<0.001). Manipulative techniques, such as indentation gonioscopy and asking the patient to look towards the gonioscope mirror, were performed in all patients to confirm the presence of peripheral anterior synechiae but their extent and nature was not recorded in all patients especially in acute ACG, and have therefore not been discussed. Post YAG iridotomy, gonioscopy was repeated only to confirm the presence of peripheral anterior synechiae. All patients underwent a Nd-YAG iridotomy in both eyes, following which the IOP control was recorded [Table:6]. Iridotomy alone controlled the IOP in 66.7% of subacute eyes and 12.9% of the acute. Medical therapy, that is pilocarpine and/or timolol, was additionally required for 35.5% of the acute eyes, 12.1% of the subacute, and 30.0% of the chronic cases. 70.0% of eyes in the chronic subgroup required a trabeculectomy, as against 51.6% in acute ACG and 21.1% among the subacute glaucoma eyes.
The success rate of the surgery at 3 months was maximal in subacute eyes and was the lowest in the chronic group. The difference between the subtypes was significant (p<0.001). 30 patients were lost to follow-up.
Visual fields were possible in only those patients with a vision of 6/60 and above, that is, 280 eyes and were unreliable in 24. 101 were performed on the Humphrey visual field analyser, and the rest on the Goldmann perimeter. A cluster of ≥2 central points depressed by ≥5 dB compared with surrounding points, a single point depressed by ≥10 dB or difference of ≥5 dB across the nasal meridian at ≥2 contiguous points were taken to indicate an early glaucomatous damage. If the Glaucoma Hemifield Test was "within normal limits", none of the focal changes enumerated above were present but the MD had a p<2%, the field was considered as equivalent to a generalised constriction as seen on Goldmann perimetry. The other scotomas were diagnosed by their position and extent. Acute and subacute glaucoma eyes had normal fields in 61.1% and 72.5% of eyes. Chronic angle closure eyes showed a generalized constriction of the field in 76.4% and residual temporal and/or central islands of vision in 13.2% [Table:7]. There was a highly significant difference between the chronic versus acute/subacute subtypes. The difference between acute and subacute was less significant (p<0.01).
Examination of the contralateral eye was recorded simultaneously. This was used to determine the frequency of bilaterality among the subtypes of ACG, or the presence of a "fellow" or unaffected eye. There was no difference when the sexes were analysed in the subacute and chronic subgroups, but there was a significantly higher incidence of bilaterality in females having acute angle closure glaucoma (p<0.05). Bilaterally affected eyes were seen in 95.5% of subacute ACG, 64.1% of chronics, and only 35.5% of acute ACG. Reciprocally, fellow or unaffected eyes were commonest in patients with acute ACG, 62.1% [Table:8]. Some second eyes had other subtypes of ACG but all had potentially occludable angles.
We have characterised the three subtypes of angle closure glaucoma seen in a large referral hospital in north India on the basis of age, sex, symptomatology, examination, and management. Exclusion of patients having undergone a prior cataract or glaucoma surgery may have altered the data to a certain extent, but was necessary to identify the subtypes.
Iridotomy alone or with topical medication was sufficient to control the intraocular pressure in about half the acute eyes, three fourth of the subacute, but only 30% of the chronic sub group. However we have been doing it in all cases of angle closure glaucoma and have had some surprising successes despite the prelaser gonioscopic picture. Other studies have documented impressive results following a surgical iridectomy.,
We have attempted to separate the three acknowledged subtypes of ACG into identifiable entities, but found a considerable overlap of clinical features. It may be that ACG presents as a spectrum of symptoms and signs because of dissimilar pathogenic mechanisms. Further work is required to determine if the apparent similarities between the acute and subacute subtypes as compared to chronic ACG, could be traced to disparate anatomic or pathophysiological factors.
The authors thank V.K. Chabra for his assistance with statistical analysis.
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