Query:
It is commonly advised to wait atleast 3 months post op ,preferably 6 months after cataract surgery before doing YAG capsulotomy for pre existing PC plaques or very early PCO.
What is the exact rationale behind it?
One school of thought I have been told is that by 6 months post op almost all cases undergo a posterior vitreous detachment (PVD) and the PVD restricts /dampens the shock waves from the laser delivery from getting directly transmitted onto the retina especially through the vitreo-retinal attachments around the macula and optic disc as these attachments do not exist after PVD. This is supposed to restrict the spring coil effect of the vitreous on the retina and reduce the incidence of Retinal detachment and macular edema post YAG.
If this is correct then one can do post op YAG capsulotomy as soon as there is a clinically evident PVD by direct visualisation or B Scan instead of a time restriction.
I would like a clarification on the above.
I have personally seen some very experienced surgeons using 30 G needles through self sealing openings at limbus to mechanically go behind the IOL and create an opening in the PC. The rationale given was that it totally avoids the shock effect of the laser on the vitreous and retina and minimizes the undesirable RD and macular edema.
I would like comments/views on the above manual capsulotomy.
Any other recommended precautions/guidelines for a post op Yag capsulotomy in terms of energy delivery quantum and mode?
Responses
No. 1
The rationale behind doing YAG-caps 3 months after cataract surgery is
1. PVD will settle as you have mentioned.
2. The zonules which become weaker by surgical manipulation need some time .
In case of emergency,I do the capsulotomy with minimal power of 0.2mj, single burst mode and restrict my number of shots (<6). It is possible if you try the CRUCIATE technique. The manual capsulotomy does always carry the risk of infection, vitreous prolapse into AC. Instead I prefer doing PC polishing with bi-manual method whenever there are Elschnig’s pearls.
No:2
I have personally seen some very experienced surgeons using 30 G needles through self sealing openings at limbus to mechanically go behind the IOL and create an opening in the PC. The rationale given was that it totally avoids the shock effect of the laser on the vitreous and retina and minimizes the undesirable RD and macular edema.
30G needle capsulotmy is safe, preferably should be done 3.5mm away from limbus in pars plana area, to cut capsule going from behind the IOL. It has to be done in OT under strict sterilization.
No. 3
There are number of complications associated with YAG- capsulotomy. Retinal detachment, CME, ERM formation,and endophthalmitis due to release of trapped commensals from the bag, subluxation / dislocation of IOL. Fortunately all these are rare.
In our observation we have noticed Retinal detachment in only 3 cases after YAG capsulotomy for 900 eyes in last two years, which comes to 0.3 percent. However, the numbers will rise when years get accumulated. Main reason for detachment is clearly PVD induced breaks. Once you open post capsule by any means ( YAG or mechanically by needle or during surgery) hyaluronic acid starts leaking out, leading to syneresis and PVD. Patients who are already predisposed, like high myopes or patients with lattice degeneration, are at risk. It is better to delay YAG capsulotomy till natural PVD occurs, particularly in these high risk candidates. But if you have to do it early, it is necessary to keep patient informed about signs of PVD, RD. It is better to wait for 3 months, as by that time, the capsule is fibrosed and lens has achieved its final position. So there will not be any shift in IOL position and also, inflammation induced will be less.
If there is anterior capsular phimosis, cut it first by radial bursts. This eliminates the risk of subluxation or dislocation and many times also reduces refractive error in the patient.
For plate haptic lenses keep opening 3.5 to 4 mm.
On table post capsulorrhexis with optic capture can be done. However the effective power of IOL changes and there are chances of post operative refractive errors.
For multofocals, if the posterior capsulorrhexis is not centered, one can induce more optical problems. As the capsule fibroses, it may shift the IOL unpredictably at times. There is an increased risk of CME, endophthalmitis, retinal detachment. The actual risk may be 1-2 percent so in 100 cases there may not be any with these problems. Of course this manoeuvre requires considerable amount of skill which only a highly experienced and skilled surgeon can do repeatable and there will be definitely less problems with these procedures in his hands. We do not touch post capsule during surgery. We explain the patient immediately after surgery that there is this plaque on capsule which is risky to remove during surgery. So we will clear that by Yag LASER after few months. Surprisingly not many patients actually complain about vision in many cases as plaques usually get thinner initially. After 3 months, if patient does have complaints, we perform YAG CAPs after careful fundus checking for any lattice or doubtful areas. These should be lasered at least 10 daysprior. Post YAG CAPs steroids and antiglaucoma should continue for 7 days. Refraction should be done again.
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