|Year : 2004 | Volume
| Issue : 3 | Page : 211-4
Modified needle drainage. A safe and efficient technique of subretinal fluid drainage in scleral buckling procedure.
R Azad, A Kumar, Yog Raj Sharma, Rajpal
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All Institute of Medical Sciences, New Delhi, India
|Date of Submission||09-Jul-2002|
|Date of Acceptance||01-Feb-2004|
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All Institute of Medical Sciences, New Delhi
| Abstract|| |
PURPOSE: To compare modified needle drainage (MND) with conventional drainage (CD) of subretinal fluid (SRF) as described by Schepens in surgery for primary rhegmatogenous retinal detachment. METHODS: Prospective randomised clinical trial of 80 patients undergoing scleral buckling with subretinal fluid drainage for primary rhegmatogenous retinal detachment. In 40 patients modified needle drainage of subretinal fluid (SRF) was done using a perpendicular trans-scleral entry with a 26-gauge needle and the appearance of SRF in the hub of needle as end point. In 40 patients conventional drainage was done as described by Schepens using a diathermy needle. Adequacy of SRF drainage, intraoperative complications, anatomical and functional outcome were noted. RESULTS: 100% adequate drainage was achieved in all cases. The complication rate was 32.5% (n=13) in the CD group and 15% (n=6) in the MND group. In the CD group, 17.5% (n=7) patients had subretinal haemorrhage and in 2 eyes it was clinically significant. In the MND group 15% (n=6) of cases had subretinal haemorrhage and in one patient it was clinically significant. In the CD group, more serious SRF drainage complications were observed; these were absent in the MND group. CONCLUSION: Modified needle drainage is a safe and effective procedure for SRF drainage. In comparison with CD, MND is technically easy, less cumbersome and requires no special equipment.
Keywords: Retinal detachment, subretinal fluid, conventional drainage, modified needle drainage.
|How to cite this article:|
Azad R, Kumar A, Sharma YR, Rajpal. Modified needle drainage. A safe and efficient technique of subretinal fluid drainage in scleral buckling procedure. Indian J Ophthalmol 2004;52:211
|How to cite this URL:|
Azad R, Kumar A, Sharma YR, Rajpal. Modified needle drainage. A safe and efficient technique of subretinal fluid drainage in scleral buckling procedure. Indian J Ophthalmol [serial online] 2004 [cited 2014 Dec 20];52:211. Available from: http://www.ijo.in/text.asp?2004/52/3/211/14589
The external drainage of subretinal fluid (SRF) is the most critical step in the scleral buckling procedure for primary rhegmatogenous retinal detachment. It is fraught with possible serious complications such as subretinal haemorrhage, retinal perforation, vitreous loss and retinal incarceration, which can compromise the functional and anatomical outcome of the surgery. These complications can result in an additional procedure or the subretinal haemorrhage can cause irreversible damage to photoreceptors; this can be most damaging if the macula is involved.
Schepens described a method of SRF drainage (henceforth called the conventional method), which has been used widely and successfully in retinal detachment (RD) surgery. The newer methods of SRF drainage described in the literature are the 25-gauge needle drainage (Charles' technique), suture needle drainage and argon laser drainage. ,,,,, In our earlier pilot study of SRF drainage using the Charles technique, we had noticed an increased incidence of subretinal hemorrhage. In order to obviate this complication we modified Charles' technique into what we have termed the modified needle drainage (MND) technique. A 26-gauge half-inch disposable needle attached to a 2ml glass syringe with the plunger removed is introduced perpendicularly through the sclera till a bead of fluid is seen in the hub of the needle. At this point the needle is immediately withdrawn to permit spontaneous SRF drainage.
Pressure is applied from opposite quadrants and anterior to the drainage site to facilitate subretinal fluid drainage. If adequate drainage is not achieved the procedure is repeated at a different appropriate site. This technique has the advantage of a small self-sealing sclerotomy and short passage through the vascular choroids because of perpendicular entry. In a tangential subretinal needle entry as described by Charles, the chance of choroidal damage increases with a higher chance of choroidal bleeding.
A pilot study of 15 cases using MND showed good functional and anatomical success and fewer drainage related complications. Hence a randomised controlled trial of this new technique (MND) with the conventional method of SRF drainage was designed to study the safety and efficacy of the new technique.
| Materials and Methods|| |
Eighty cases of primary rhegmatogenous retinal detachment without proliferative vitreoretinopathy that underwent scleral buckling procedure with drainage of SRF were randomised. All cases of reoperations and bleeding disorders were excluded from the study. Bleeding disorders were excluded by enquiring into history of any bleeding diathesis and by laboratory tests of bleeding and clotting time. Detailed history, systemic examination, anterior and posterior segment evaluation were recorded. The fundus photographs were taken using a Carl Zeiss digital camera. The cases were allocated to the MND and CD groups by randomisation tables so that each group had 40 cases.
In all the cases the standard technique of retinal detachment surgery was followed. After the breaks were identified and localised, cryopexy was performed and scleral sutures were placed for the scleral buckling procedure. The drainage site was localised where the height of retinal detachment was greatest, preferably close to the lateral or medial recti near the equator and when possible in the bed of the buckle, away from the cryopexy sites and vortex veins.
In conventional drainage a 5-mm meridional sclerotomy was performed. Diathermy of scleral lips was performed. A T1 Electrode with Mira (Medical Instruments, Research Associates, Inc. Walltham, MA, USA) diathermy machine was used. Then the knuckle of choroids that appeared was perforated with the diathermy electrode. Once the drainage of SRF was completed, the preplaced sutures were tied to close the sclerotomy.
MND was performed using a 26-gauge disposable Z\x" long needle attached to a 2-ml syringe without the plunger. The needle was inserted perpendicular to the ocular surface at the site previously localised for the drainage and as soon as a bead of fluid was seen in the transparent hub of the needle, the needle was withdrawn allowing spontaneous drainage of the SRF. The maximum needle penetration from the scleral surface was about 2 mm; If no fluid was noted in the hub of the needle, the drainage site was examined by indirect ophthalmoscopy. If no complication was noted, drainage was reattempted at the same site or an alternative site.
Two experienced vitreoretinal surgeons performed all the surgeries and recorded the findings.
Adequacy of drainage was assessed by indirect ophthal-moscopy as described by Aylward et al and graded as follows:
Grade 1. Total drainage (ž 75%)
Grade 2. Partial but adequate for buckle indent (ž 50%)
Grade 3. Partial but inadequate for buckle indent
Grade 4. Dry tap
By comparing preoperative and drainage height of detachment, the percentage of drainage was assessed as 100%, 75%,50% and less than 50% to determine the volume of subretinal fluid drained.
Complications such as subretinal haemorrhage, retinal perforation, retinal incarceration and vitreous loss were recorded and managed accordingly.
Subretinal hemorrhage was clinically classified as Minimal (less than one disc area in size); Small (between one to four disc areas in size); Large (more than 4 disc areas in size).
Small and large haemorrhages were considered significant, and it was considered clinically significant if the macula was involved. Once the drainage of SRF was completed, the explant was positioned and buckle sutures were tied thereafter to obtain the desired buckle indent; the encircling band was tied thereafter. The patients were followed up in the postoperative period on day 1, day 7, at month 1 and month 3. Visual acuity, intraocular pressure, anterior segment and posterior segment evaluation with particular reference to drainage site were done. The results were tabulated and statistically analysed using Pearson's chi-square test for statistical significance with NH analytical software Statistix.
| Results|| |
Forty patients each underwent MND and CD of SRF. The mean age was 44.05±10.16 years and 45.10±10.18 years in MND and CD respectively. The other patient parameters in two groups are given in [Table - 1]. No statistically significant difference was noted with respect to gender, refractive errors and duration of detachment in either group [Table - 1]. 100% drainage was achieved in 15 (37.5%) cases in MND and 17 (42.5%) cases in CD (P=0.81). 75% drainage was achieved in 20 (50%) cases in MND and 17 (42.5%) cases in CD (P=0.65). 50% drainage was achieved in 5 (12.5%) cases in MND and 6 (15%) cases in CD (P=1.00). The success of drainage as assessed by the percentage of drainage was comparable in both groups. Successful drainage (total or partial but adequate) was achieved in all 80 eyes [Table - 2].
Compared to the CD group, more attempts were required in the MND group to obtain successful drainage. Eight cases in the MND group required more than one attempt and 3 cases in the CD group required more than one attempt. The difference was not statistically significant (p <0.43). An analysis of the complications did not show an increased incidence of subretinal haemorrhage in the eyes in the MND group with more than one attempted drainage site [Table - 3].
The differences in serious SRF drainage related complications between the two groups were not statistically significant though these complications occurred more often in the CD group. The difference between the two groups was 17.5% [Table - 4]. This was not statistically significant (P = 0.76) but clinical significance was obvious. Three patients in the CD group needed pars plana vitrectomy. Two patients had retinal incarceration and one patient had large subretinal haemorrhage. All these patients developed proliferative vitreo retinopathy (PVR) of grade C3 or higher.
Fifteen patients (30%) in the CD group and 5 patients (10%) in MND group needed intravitreal air injection. The difference was statistically significant (P=0.0253).
| Discussion|| |
Jules Gonin made the landmark observation regarding the importance of retinal breaks in retinal detachment surgery. Since then the technique of scleral buckling has been improved and modified. The drainage of subretinal fluid is the most critical step in the surgery. Schepens described the conventional method of drainage using sclerotomy, diathermy and perforation of the choroids., This technique was later modified using the 10-0 monofilament nylon suture needle and argon laser for perforation of the choroids. , These techniques need large sclerotomy and have a high incidence of associated complications, ranging from 5.6% to 17.5%.,
Charles described needle drainage with a 25-gauge needle attached to a tuberculin syringe introduced tangential to sclera into the subretinal space. Ibanez et al compared argon laser choroidotomy with needle drainage as described by Charles. They noted subretinal haemorrhage in 13% of the cases in argon laser choroidotomy and 16% in needle drainage. Retinal incarceration and retinal perforation occurred only with argon laser choroidotomy. Burton et al performed needle drainage in 45 cases as described by Charles and reported subretinal haemorrhage in 10 of these (22.2%). This technique of needle drainage as described by Charles did not become popular because of the increased contact of the needle with the vascular choroids and hence the increased risk of subretinal haemorrhage. Hence to minimise the choroidal trauma, we modified this technique by making direct and perpendicular transcleral entry by a 26-gauge needle. Our end point of observing the subretinal fluid in the hub of the needle allowed the needle entry in a controlled manner to a desired depth. No more than 2 mm of needle penetration was attempted at the selected site for subretinal fluid drainage. This also decreases the risk of retinal perforation and vitreous loss. The small size of sclerotomy (450 microns, the diameter of the 26 gauge needle) reduces the risk of retinal incarceration. The short passage of the needle through the choroids reduces the risk of SRH and the drainage is more controlled.
In comparison the conventional drainage carries the risk of subretinal haemorrhage, retinal/vitreous incarceration and retinal perforation because of the large opening of choroids and resultant uncontrolled drainage. Also the modified needle drainage ensures that the choroidal opening is small, which may not be the case in conventional drainage wherein tangential entry of needle or blade tip can inadvertently result in larger choroidal opening than desired.
In this study we found that the success rate of drainage was equal in both the groups. More than one attempt was required in more cases in the modified needle drainage group, but this did not increase the risk of subretinal haemorrhage or other complica-tions. An analysis of complications showed a higher incidence of subretinal haemorrhage and other serious complications in conventional drainage group. We believe that a statistically significant difference was not obtained because of the low number of cases in each group. However a 2-fold increase in complications in conventional SRF drainage was noted compared to the MWD technique. This highlights the safety of the modified needle drainage technique. Thus in our study more cases needed intravitreal air injection to counter ocular hypotony in conventional drainage group. This may also be because drainage tended to be more complete in the conventional drainage group. This is another disadvantage of the conventional drainage technique. The MND is cheaper as it does not require instruments like a diathermy machine, Beaver's Knife to peneterate sclera and sutures to close the sclerotomy.
In conclusion, modified needle drainage is a safe and efficient technique that can be easily learnt and applied. It has the added advantage of not requiring any additional surgical equipment. At our centre we have been using the modified needle drainage as the sole technique in SRF drainage in RD surgery for over three years. The slightly higher incidence of more than one attempt for SRF drainage is insignificant and still permits efficient SRF drainage with a considerable saving of time compared to the conventional method.
| References|| |
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[Table - 1], [Table - 2], [Table - 3], [Table - 4]
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