|Year : 1983 | Volume
| Issue : 6 | Page : 745-748
Cataract surgery in myopia
Prof Ophthalmology, Medical College, Jabalpur, India
R K Mishra
Prof Ophthalmology, Medical College, Jabalpur
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mishra R K. Cataract surgery in myopia. Indian J Ophthalmol 1983;31:745-8
In this short paper I am presenting a comparative study of myopic and nonmyopic eiyes operated for cataract surgery. Myopia produces certain structural changes in the eye. These changes not only effect the sensory structures like the retina and choroid but also influence the strength of the scleral coat and the structure of vitreous body. Both of these play an important role in the ultimate outcome of surgery.
In this paper 122 cases of myopes and equal no. of nonmyopes have been closely studied in the postoperative period for different complications that are met with in cataract surgery.
| Material|| |
122 cases of senile cataract were selected from amongst known Axial myopes of over 4 D between the ages of 55 years to 65 years. Uncertaincases were excluded. Those associated with Diabees and Glaucoma were excluded. An identical no, and type of cases were selected from non-myopic eyes. These patients who could not cooperate in the postoperative examination under slit lamp microscopy or could not come for follow up were dropped and thus a final of 122 cases from each series were studied.
| Method|| |
The myopes were divided in three groups:
1. Low myopes ... 4 D to 5.5 D ... 60 cases
2. Moderate Myopes ... 6 D to 10 D ... 42 cases
3. High Myopes ...Above 10 D ... 20 cases
They all were known Axial Myopes.
These cases were compared with an identical and equal number of non myopic cases on the following points:
1. Vitreous displacement.
2. Corneal decompensation.
3. Choroidal detechment.
4. Retinal detechment.
6. Intra ocular tension.
7. Post operative Visual gain.
All these cases were subjected to identic surgical procedure and post operative foil up:
| Procedure|| |
Operated under local aneasthesia. Fornix based flap. Three presection limbal groove sutures. Khife section. Peripheral iredectomy. Chymotrypsin. Cryo extraction. Wound closer. Funduscopy. Reformation of A.C. with Air/saline. Subconjuctival Garamycin. Dress with Atropin Antibiotic. Uniocular Bandage for 5 days. Daily dressing. All cases were examined under slit lamp microscope and were subjected to Aplanation Tonometry from second dressing onwards.
| Observation and comments|| |
The problem of vitreous displacement is the single most important factor in cataract surgery. One of our major goal in cataract surgery is to prevent vitreous loss. Whatever technique one uses, the aim is to prevent pressure upon and on the vitreous at the time of actual lens delivery. The pressure comes commonly by the lids, extra ocular muscles or heamatoma in the orbit or choroid. At times the pressure is built by the trapped aqueous behind the vitreous. An important factor is the scleral fitness. In myopes this factor is of special importance. The infirm sclera tend to collapse. The structure of vitreous itself certainly influneces the loss of vitreous. The vitreous in any high myope is structurally different from a healthy vitreous. In the present series our findings have been as fllows:
After Vit. Loss Anterior vitrectomy was performed in all cases.
It is our impression that incidence of vitreous disturbance is positively higher in myopes and every care must be taken in anticipation to prevent it.
The three main factors which make the eyes more prone to vitreous loss are (1)
Fluidity of vitreous (2) Incidence of trapped aqueous that has seaped behind the vitreous and (3) Scleral weakness allowing it to sag after section.
Probably the correct nomenclature will be cilio choroidal detechment. In most cases it is actually a massive chroidal aedema. The anatomy of the ant. uvea resembles blood sinuses with single layer endothelial wall with no muscular coat and practically no connective tissue fibrillae. The sudden release of external pressure leads to their engorgement and transudation through their thin wall is easy. The intra ocular pressure acts against this transudation. Surgical decompression on section helps this transudation. The intravascular colloidal tension influences the determining force. Prolonges chroidal detechment leads to pigmentary disturbances.
In our series we find the incidence to be as follows:
Most of these detechments are seen in the first week of operation and tend to disappear spontaneously. Myopia does not seem to increase the incidence of choroidal detechment. In our seres the incidence has been actually less amongst the myopia.
Incidence of Ret. Detechment amongst the akhakic eyes is very much higher than Phakics. This indicates that the eyes with cataract is sick eye andremoval of lens further complicates this wekness.
Incidents of detechment in myopic aphakics is still higher. In the present series, the incidence of detechment in myopes was found to be three times as high as in the nonmyopic series.
This suggests that cataract surgery in myopes must be taken seriously. Unnecessary operations with immat. cataract should be avoided. Further these cases of potential cataract operations must receive a good periodical check up by a retinal surgeon and they should even receive a prophylactic treatment prior to cateract surgery. Even after cataract surgery they should be regularly checked for at least 6 months for any evidence of retinal hole or tear.
Incidence of macular aedema has been quoted to be as high as 30% and appearing as late as 1 year to 1 1/ 2 years. In our series the incidence is smaller.
The aetiology is debated but it generally considered that the osmotic tension disturbance created by vitreous movement is responsible for it. Iritis and vitiris have also been blamed by producing infamatory exudation. In our series the incidence has been as follows:
In our experience the incidence of maulopathy is not higher in myopes than in nonmyopes. If any thing it is lower.
Rise of intraocular _tension in the immediate post operative period of some times complicated cataract surgery. It is suspected that use of chymotrypsin increases this complication by creating a filtration block by chunks of broken suspensory ligaments. We tried to assess this by recording the intraocular tensionin all these cases from 48 hours onwards during daily slit lamp microscopy at the time of daily dressing. Applanation tonometer was used for this purpose.
We were surprised to find that a good number of cases did show rise of intraocular tension in third to 4th day. This was usually accompanied by complaint of pain in the eye by the patient. In our observation 5.8% of cases showed tension rise above 24 mm Hg. The two series did not show any difference. This suggested to us that pain in third or 4th day of operation calls for a check up of IOT. We also noticed that timely medication promtly controlls the tension. In our series use of Atropin, corticosteroiss and Diamox controlled the tension to normal within 2 weeks.
Occurrence of bullous Keratopathy is now being recognised as a frequent complication of cataract operation. The American literature suggests the incidence to be as high as 5%. 20,000 cases ever year in U.S.A.
I do not know what must be incidence in our own country but it must be similar if not higher.
In our series we have a disadvantage in that our observation is only for a short time. Many of these complications appear much later.
In almost all cases where we found evidence of corneal aedema, they were seen in those cases where either there was a vitreous loss or where the vitreous was found in the anterior chamber. It seems that contact of health vitreous with the endothelium is mostly responsible for this corneal change.
The incidence in our series was more in myopic series but then the incidence of vitreous loss too was more in that group.
It is my impression that his complication can be avoided by preventing vitreous loss, adhesion between Iris and incase a contact has established between vitreous and the endothelium then breaking that adhesion and performing vitrectomy promptly.
Finally the Visual Gain:
Post operative visual gain in high myopes is significantly low. In our series as low as 50 of cases had final acuty less then 6/60. In myopes above-6 D. The structural damage in myopia is usually the main factor of reduced vision rather than the immatured cataract itself. One should not be too enthusiastic about removing immatured cataracts in myopes only because the patient is pressing for the operation. Ultimately he is a dissatisfied patient.
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6], [Table - 7], [Table - 8], [Table - 9]