Year : 1996 | Volume
: 44 | Issue : 3 | Page : 149--155
Lens induced glaucomas - visual results and risk factors for final visual acuity
N Venkatesh Prajna, R Ramakrishnan, R Krishnadas, N Manoharan
Aravind Eye Hospital & Post Graduate Institute of Ophthalmology, Madurai, India
N Venkatesh Prajna
Aravind Eye Hospital & Post Graduate Institute of Ophthalmology, Madurai 625 020
Lens induced glaucomas are a common occurence in India. An attempt was made to understand the clinical modes of presentation and post operative visual results in 93 patients with lens induced glaucoma, 49 phacomorphic and 44 phacolytic, attending our institute during 1994. All these patients were subjected to a planned extracapsular cataract extraction. Forty four percent had a posterior chamber intraocular lens implantation following surgery. Fifty seven percent eyes with phacomorphic glaucoma and 61% with phacolytic glaucoma recovered visual acuity of 6/12 or better. There was no significant difference in the final visual acuity between those patients who had an intraocular lens implanted and those who did not (P=0.18). Univariate analysis was performed for selected risk factors such as age, sex and duration of glaucomatous process as predictors of final visual acuity and odds ratios with 95% confidence intervals were calculated. Patients with age more than 60 years (OR=2.7, 95% CI=1.04 - 6.93) and in whom the glaucoma was present for more than 5 days (OR=3.1, 95% CI=1.21 - 8.13) had a significantly higher risk of poor visual outcome post-operatively.
|How to cite this article:|
Prajna N V, Ramakrishnan R, Krishnadas R, Manoharan N. Lens induced glaucomas - visual results and risk factors for final visual acuity.Indian J Ophthalmol 1996;44:149-155
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Prajna N V, Ramakrishnan R, Krishnadas R, Manoharan N. Lens induced glaucomas - visual results and risk factors for final visual acuity. Indian J Ophthalmol [serial online] 1996 [cited 2021 Sep 23 ];44:149-155
Available from: https://www.ijo.in/text.asp?1996/44/3/149/24575
With a cataract backlog of around 12 million and annually increasing at an estimated rate of 3.8 million, it is not surprising that the occurrence of lens induced glaucomas is not an infrequent event in India., Though not all inclusive, these lens induced glaucomas (LIG) are either secondary angle closure glaucomas (phacomorphic glaucomas) or secondary open angle glaucomas (phacolytic glaucomas). Irrespective of these modes of presentation, the treatment has been oriented towards a single focus, namely, removal of the cataractous lens. Historically, intracapsular cataract extraction has been the preferred technique for these lens induced glaucomas,,, though there is a perceptible shift towards extracapsular cataract extraction in the recent times. Reports of the safety of posterior chamber intraocular lens implantation following a planned extracapsular cataract extraction in phacolytic glaucomas lend credence to this modern mode of management of this condition.,
Whatever be the mode of surgical intervention, the prognosis for good post operative visual recovery in these conditions remains guarded. In order to evaluate this information and to collect other relevant details of lens induced glaucomas, we decided to do a retrospective study to answer the following questions.
(a) How common are these clinical entities and what may be the modes of clinical presentation?
(b) What proportion of these cases attain a good postoperative visual acuity (equal to or better than 6/12)?
(c) Are there any specific risk factors to determine final visual acuity in these patients?
MATERIALS AND METHODS
This retrospective study was conducted by reviewing the case reports of patients with a diagnosis of lens induced glaucoma, attending the paying outpatient department of our institution over a period of one year (January to December 1994). A total of 98 such patients attended the hospital, but 5 patients were excluded from the present analysis, 3 of whom had prior ocular hypotensive management elsewhere and 2 patients who failed to return for followup examination. The analysis of the present study was performed on the rest of the 93 patients. A detailed clinical examination included the status of the lens and the anterior chamber depth of the other eye assessed by slit lamp biomicroscopy, applanation tonometry by Goldmann applanation tonometer and gonioscopy of the fellow phakic eye. The depth of the anterior chamber was assessed by directing the slit lamp beam adjacent to the limbus and the anterior chamber was considered to be shallow if its depth was less than 1/4th of corneal thickness.
Phacomorphic glaucomas were recognized by the subjective complaints of pain and redness associated with the presence of corneal oedema, shallow anterior chamber, an intumescent cataractous lens and intraocular pressure above 21 mmHg. Preoperative measures to decrease intraocular pressure included topical application of timolol maleate 0.5% twice daily supplemented with oral acetazolamide 250 mg four times a day, and oral glycerol 50% 1 oz twice a day. Mannitol 200 ml of 20% was given intravenously just before surgery for a period of thirty minutes.
Phacolytic glaucomas were diagnosed by the presence of pain, corneal oedema, a normal or deep anterior chamber containing floating lens particles and/or pseudohypopyon in severe cases and the presence of a white hypermature morgagnian cataractous lens. The attempt to control intraocular pressure in these cases was made by the topical application of betamethasone 0.1% eye drops six times a day, timolol 0.5% eye drops twice a day, and atropine 1% eye drops twice a day, supplemented with oral acetazolamide 250 mg four times a day. Pilocarpine 2% was not used as a hypotensive agent in either of these groups. The intraocular pressure was then measured by applanation tonometry to assess the change following these hypotensive medications. The management of all these eyes was same irrespective of their response to these hypotensive measures.
After obtaining informed consent and explanation of relatively guarded prognosis, the patients (irrespective of the diagnosis of either phacomorphic or phacolytic glaucoma) were subjected to a traditional planned extra capsular cataract extraction (ECCE) under retrobulbar anaesthesia. A posterior limbal section was made and the anterior chamber was entered in a controlled manner. A can opener capsulotomy was performed and the nucleus was expressed with a pressure-counter pressure technique. The remaining cortical matter was aspirated with a manual hand held Simcoe cannula. Viscoelastics were used to deepen the anterior chamber if and when necessary. A decision to implant a posterior chamber intraocular lens (PC IOL) was taken on the following category of patients: those whose fellow eye was pseudophakic, or which had a clear lens or very early lens changes, and those who insisted on having an intraocular lens implant. A peripheral iridectomy was performed on all the patients. A subconjunctival injection of dexamethasone (2 mg) and gentamicin (20 mg) was given at the end of the procedure.
Subsequently the patients were kept in the hospital for a postoperative period of three days. Topical medication comprising of a combination of chloramphenicol and dexamethasone was applied six times a day. A short acting cycloplegic was used if and when necessary - the main objective being prevention of posterior synechiae formation. Systemic antibiotics or systemic steroids were not used in any patient. They were then discharged with instructions to use a topical antibiotic steroid combination for a period of 6 weeks. During the followup, refraction was performed using a Snellen visual acuity chart by a trained optometrist and the postoperative intraocular pressure was also measured by Goldmann applanation tonometry. A good intraocular pressure control was defined as a final postoperative intraocular pressure of ≤ 21 mmHg, without the need for any antiglaucoma medication. A total ophthalmological evaluation including slit lamp biomicroscopy was performed. The posterior pole was evaluated using a direct ophthalmoscope and a 90D lens evaluation on the slit lamp.
A Chi-square test was used to determine any association between the age and sex distribution of patients who participated in this study. The association between the final visual acuity and the two study subgroups (phacomorphic and phacolytic) and between the two procedures (ECCE and IOL) were also analysed using Chi-square test. The analysis comparing selected characteristics such as age, sex and duration of raised intraocular pressure between those patients who regained good visual acuity (≥=6/12) and who did not were performed. Odds ratios (OR) were calculated with 95% confidence intervals (95% CI).
Phacomorphic glaucomas were present in 49 patients and phacolytic glaucomas in 44 patients. The mean age at presentation was 62±10 years (range 43-85) for phacomorphic glaucomas and 63±11 years (range 42-85) for phacolytic glaucomas. The age curve represents a minimal skew towards older age group in case of phacolytic as compared to the phacomorphic cases. There was a slight female preponderance (54%) compared to the male population (46%) which implies a statistically marginally significant difference [Table:1]. However there was no statistical significance difference when compared by the two subgroups.
When the groups were combined, examination of the lens status in the fellow eye revealed that 55% had immature cataracts, 34% were aphakic, 6% were pseudophakic, 2% had mature cataracts, 1% had a clear lens and 1% was one eyed [Figure:1]. However examination by subgroups revealed that in case of patients with phacomorphic glaucomas, the status of the fellow eye was predominantly immature cataracts (about 80%) while aphakia contributed 12%. Sixty percent of the fellow phakic eyes of phacomorphic glaucomas had shallow anterior chamber and a gonioscopic angle width of less than 20 degrees. Analysis of the fellow eyes of patients with phacolytic glaucoma showed that they were predominantly aphakic (72%) and immature cataracts contributed 27% [Figure:2]. None of the fellow phakic eyes of phacolytic glaucomas had shallow anterior chamber and all these eyes had a wide open angle by gonioscopy.
The total mean preoperative intraocular pressure was 42±12 mm Hg (range 22-70) while it was marginally higher for phacomorphic (45±12 mmHg) than for phacolytic (40±11 mmHg). After the administration of hypotensive medications, 55 eyes (60%) had an intraocular pressure of less than 30 mmHg. The duration between onset of pain and surgery varied from 1 day to 45 days. The follow-up ranged from 40 to 126 days with a mean of 60 days and the visual acuity at the last followup was taken as the postoperative visual acuity. A corrected visual acuity of 6/12 or better was taken as good visual acuity and accordingly 57% of the phacomorphic glaucomas and 61% of the phacolytic glaucomas recovered to a good visual acuity [Table:2]. Five patients (10.2%) with phacomorphic and 6 patients (13.6%) with phacolytic glaucoma had poor visual recovery(< 6/60). There was no statistical difference between the two groups on the final postoperative visual recovery. There was also no statistically significant difference on the attainment of good postoperative visual acuity (6/12 and better) between those patients who had an intraocular lens and those who did not [Table:3]. The intraocular pressure was controlled in 95% of patients (<= 21 mmHg) without the need for any antiglaucoma medication [Figure:3] and the mean postoperative final intraocular pressure was 14±6.5 mmHg for the phacomorphic group and 12±2.6 mmHg for phacolytic group. At presentation when the age of the patients was greater than 60 years, there was a marginally significant risk of having poor visual outcome when compared with patients younger than 60 years (OR=2.7; 95% CI=1.04 - 6.93) [Table:4]. There was a significant risk of obtaining poor visual acuity when the duration between the onset of pain and surgery exceeded 5 days (OR=3.1; 95% CI=1.21 - 8.13) [Table:4].
Though not statistically significant, males had a slightly higher risk of obtaining poor postoperative visual acuity (OR=2.2; 95% CI=0.88 - 5.66) [Table:4]. However we have to take into consideration that the mean age of the male population in our study was marginally higher (64±11) as compared to the female (61±10). Contrary to our expectations there was no statistically significant association between the level of preoperative intraocular pressure and final visual acuity (p=0.07) [Table:5]. The intraoperative and postoperative complications are shown in [Table:6] and [Table:7].
Lens induced glaucomas are a common occurrence in India, hardly surprising in a situation where the incident of cataract cases far exceeds the total number of surgeries performed currently. Though these are clinically distinct entities, they have certain common factors in that they are lens induced, they compromise the function of the optic nerve due to rise of intraocular pressure, cataract surgery is curative in these cases, and finally they uniformly share a guarded prognosis.
This study was undertaken to outline the different characteristics of glaucomas, to determine the postoperative visual results following a planned extracapsular cataract extraction and to evaluate any risk factors which may play a role in the determination of final postoperative visual acuity. It should be noted that 93 patients of lens induced glaucomas in this study belonged to the paying section of our institute, (higher socio-economic group) they could differ from the nonpaying (lower socio-economic group) patients and therefore may not reflect the true distribution of characteristics of these glaucomas in the general population.
In our study, females seemed to have a statistically marginally significant increased risk (p=0.05) of having these glaucomas. Though it is possible that these entities are more common in females because of socio economic constraints, we also have to consider the fact that the prevalence of cataract itself is more common in females than males. This finding was consistent with data from the Punjab study in India and from the Matlab study in Bangladesh. In the Framingham Eye Study as well as in the US Health and Nutrition Examination Survey, senile lens changes were more common in women.
In our study, of these two groups of glaucomas, phacomorphic was slightly more common (52.7%) than phacolytic (47.3%). The mean age of the two groups were comparable even as there was a minor skew towards the older age group in case of phacolytic glaucomas. Earlier studies had also indicated that phacolytic glaucoma occurred more commonly with increasing age, probably due to the aggregation of high molecular weight proteins over time., We also documented the status of the lens in the fellow eyes of these patients to see if there was any difference between the subgroups. A vast majority of the fellow eyes in patients with phacomorphic glaucoma had immature cataracts while most of the fellow eyes of phacolytic glaucomas were aphakic. There was no statistical difference in the preoperative intraocular pressure rise and the time elapsed between the onset of pain and surgical intervention between the two study groups.
All these patients were managed by a planned extracapsular cataract extraction after attempting to bring the preoperative intraocular pressure within normal limits. In addition, 44% of these patients had a posterior chamber intraocular lens implantation.
The surgical procedure by itself was not different from a routine extracapsular cataract extraction and there was no specific increase in the intraoperative complication rate. The rate also did not differ between both the groups of patients except for shallow anterior chamber seen in the phacomorphic group (p=0.00) [Table:6]. However the post operative period was more stormy in these cases than a regular cataract extraction and they were managed by more frequent application of topical steroids and antibiotics. The phacomorphic group had more common occurance of hyphema (p=0.05) and pupillary capture of PC-IOL (p=0.05) [Table:7].
There was no statistically significant difference in the postoperative final visual acuity between the two groups. Fifty seven percent of phacomorphic glaucomas and 61% of phacolytic glaucomas attained postoperative corrected visual acuity of 6/12 and better. None of these patients had a compromised optic nerve due to the glaucomatous process. Five patients (10.2%) with phacomorphic glaucomas and six patients (13.6%) with phacolytic glaucomas had visual acuity less than 6/60. All these five patients with phacomorphic glaucomas and four of the six patients with phacolytic glaucomas had compromised optic nerves due to the glaucomatous process itself. The reason for the visual acuity remaining poor in the rest of the two patients with phacolytic glaucoma was due to severe persistent postoperative uveitis and resultant cystoid changes in the macula. There was also no statistically significant difference in the attainment of final good visual acuity (6/12 and better) between those patients who had an intraocular lens implanted and those who did not [Table:3]. However, 17% of the aphakic group attained visual acuity less than 6/60 as compared to 5% in the IOL group. There is in itself a possibility of bias since intraocular lens was not implanted in patients who were considered a poor risk in obtaining good visual acuity.
Factors such as age and sex of the patient, and duration of the glaucomatous process which were thought to play a role in the visual outcome of these patients were analyzed. Patients above the age of 60 years had a marginally significant increase in odds of obtaining poor visual acuity. A related but not similar parallel can be drawn to studies which show that primary open angle glaucoma is more common in old age, probably due to the susceptibility of the optic nerve to damage. Our study also revealed that eventhough the disease process was slightly more prevalent among the females, males had a slightly greater risk of obtaining poor visual acuity, eventhough these were not statistically significant. This statement has to be analyzed with caution in our study, because the mean age of males in our study was more than the females and age may be a confounding factor.
There have been reports about excellent visual acuity results with intraocular lens implantations for phacolytic glaucoma., However in both the studies, the time interval between the diagnosis and the surgical intervention was less than 6 days. In our study which is a much larger series, we do not find such spectacular visual results and would like to conclude that
(a).All the surgeries performed on patients with lens induced glaucomas (irrespective of whether or not IOL has been used) should always be preceded with an informed guarded prognosis.
(b). In the context of the usage of intraocular lenses which has been proved to be safe in these glaucomas, it is natural for the patient to harbor higher expectation and hence the guarded prognosis should be adequately explained, particulary in the high risk groups such as persons above the age of 60 years and persons who have raised intraocular pressure for more than five days.
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