|Year : 1989 | Volume
| Issue : 2 | Page : 64-66
Methylcellulose-a better viscosurgical alternative for intraocular lens implantation
Akira Momose, Atsuhiro Kasahara
Director, Institute of Clinical Ophthalmology, 1 -100 Umeda, Kiryu, Gunma, 376 - 06, Japan
Director, Institute of Clinical Ophthalmology, 1 -100 Umeda, Kiryu, Gunma, 376 - 06
Source of Support: None, Conflict of Interest: None
The authors have used 2% methylcellulose in 8,000 cases of intraocular lens implant surgery during the last five and a half years. Their surgical experience and investigations have convinced them that methylcellulose is safe and effective besides being convenient and economical. It is easily autoclavable, has very low particulate matter when prepared by the author's technique, and causes minimal secondary rise of intraocular pressure. The endothelial protective function and breakdown of the blood aqueous barrier are comparable to that of Healon. The authors consider methylcellulose to be the better alternative for IOL implant surgery.
Keywords: Methylcellulose, IOL implantation, Technique of preparation, Particulate Matter, Systemic Safety, Endothelial Cell Loss, Postoperative Glaucoma.
|How to cite this article:|
Momose A, Kasahara A. Methylcellulose-a better viscosurgical alternative for intraocular lens implantation. Indian J Ophthalmol 1989;37:64-6
| Introduction|| |
The role of viscosurgical substances in intraocular surgery is well establised. Methylcellulose has been used in intraocular lens (IOL) implant surgery for a decade or more , . However, its wider use has been limited by fears about particulate contamination  , uncertainly about its effect on the endothelium and blood aqueous barrier-and paucity of reports in the literature about safe and efficacious use of the substance in a large series.
The first author has used methylcellulose prepared in his pharmacy for the last five and a half years in over 8000 cases of intraocular lens implantation. The authors found methylcellulose prepared by their technique to be a better alternative as compared to the other available viscosurgical substances. This surmise is based on the authors' surgical experience  , their studies on particulate contamination in available viscosurgical substances  , their observations on endothelial damage  and postoperative intraocular pressure  after the surgical use of different viscous substances, reported results of a study on postoperative breakdown of blood aqueous barrier  and economic considerations.
TECHNIQUE OF PREPARATION OF 2 % METHYLCELLULOSE:
The material is the medical use grade hydroxypropylmethylcellulose which is commercially available as Methocel ® E - 4M Premium (Dow Chemical Corporation). 10 g of Methocel ® E- 4M Premium is dissolved in 150 ml of B.S.S.® (Alcon Laboratories, Inc ), then warmed to about 90°C and stirred well. Ice bath chilled BSS® is added to the above solution to make it upto 500ml. This 2 % Methocel solution is poured in to a glass bottle, tightly closed by a glass stopper and preserved for one night in a refrigerator at 0°C to -10°c. The solution is then warmed to 40°C to reduce its viscosity and filtered by MILLI FIL ® PF (Millipore® : pore size 0.811) connected to a Millipore® tube pump [Figure - 1] (Alternatively, for small quantities, a 10 - 20ml injection syringe may be used instead of the pump). The filtered solution is poured into 3 ml vials and sealed with a rubber stopper and aluminium cap. It is packed in a sterilizing bag and autoclaved at 120° C for 30 minutes. Methylcellulse solution is aspirated into a 1.0ml syringe through a 16G needle when it is used or it may be contained in a special syringe developed for this purpose . At this time care should be taken not to withdraw air bubbles.
Ease of Preparation and cost
The easy preparation of a safe autoclavable methylcellulose at a minimal cost makes it extremely suitable for use. This is particularly significant in the developing countries, where few can afford a viscosurgical substnce at a prohibitive cost. Methylcellulose solution can be used in hundreds of cases for the same cost as 0.4 ml of Healon®.
The number of insoluble particles of various sizes in one ml of five viscosurgical materials were examined by HIAC PC320 particle size analyzer  (HIAC/ROYCO), [Tabe 1], at the Institute of Clinical Ophthalmology. Methylcellulose prepared by the aforementioned technique has been shown to have 10 times less particles of various sizes (1-30mm or more in diameter) as compared to Viscoat®,Amvisc® and Healon® as measured by HIAC PC- 320 particle size analyzer (HIAC/ROYCO). This is contrary to the misgivings on the score reported earlier by Rosen and co- workers  , who found a high density of particulate matter in the solutions of methylcellulose analysed by them. However, the filters used and filtration methodology employed in the samples studied by them must be different from the authors' present technique.
The medical use grade methylcellulose is hydroxypropylmethylcellulose. It consists of two molecules of glucose that bind to form cellobiose, a molecule that human bodies are supposedly unable to breakdown. The process by which methylcellulose is cleared from human bodies is at present unknown , . However, this seems to be without any clinical significance. Methylcellulose has long been used for emulsification in injectable medicines such as prednisolone acetate and hydrocortisone acetate. It has also been used orally in large doses in soft icecreams without any known side effects. The doses used intraocularly are comparatively minute and not likely to cause any toxicity.
Ease of IOL Manipulation
2 %Methylcllulose has the ideal viscosity for IOL implantation. The authors have observed that 'in the bag' placement of the IOL is easier when using methylcellulose than with more viscous Healon®. With Healon® the lens tends to be pushed back when placing the inferior haptic `in the bag',especially in an IOL with polypropylene loops. Fig. illustrates the resistance felt by the polypropylene loops in Healon and Methylcellulose respectively. The IOL sinks into methylcellulose solution smoothly by its gravity but not in Healon®.
Without considering the cost, methylcellulose may be reinjected whenever the anterior chamber tends to shallow, as it is inexpensive. Thus the disadvantage of relatively lower viscosity, if any, is easily offset in most cases. However, Healon® may be more useful in unusually hard eyes. Heal one is also more useful when cataract surgery is combined with keratoplasty i.e. the triple procedure.
Endothelial Cell Loss and Effect on Blood Aqueous Barrier
It has been observed that endothelial cell loss is lower with the use of methylcellulose during IOL implantation as compared to air , . The study done at the Institute of Clinical Ophthalmology  also demonstrates that the difference in the endothelial cell loss when using Healon® (20.7± 15.6%, 178 cases) and methylcellulose (18.1 ± 14.9% 205 cases) was not statistically significant  . It has been demonstrated by fluorophotometric study that the disruption of blood aqueous barrier with the use of methylcellulose in intraocular surgery is similar to that with sodium chondroitin sulphate or sodium hyaluronate  .
Post-operative glaucoma is not a frequent problem with methylcellulose, especially if it is washed out at the end of surgery. The occurrence of intraocular pressure (IOP) over 25 mm Hg postoperatively in a series of 205 cases was 7.3 %  . However no patient had any symptoms or required any treatment, as the IOP returned to normal in all cases within a few days. This may be attributed to the water solubility of methylcellulose which eases the drainage of methylcellulose from the anterior chamber. A lower count in particulate matter of methylcellulose which may obstruct the trabecular meshwork, may also account for its low potential for elevated IOP. The authors, therefore, consider methylcellulose to be a better alternative for IOL implantation and advocate its routine use for the purpose.
| References|| |
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Rosen, E.S., Gregory, RP.F.,Bamett, F.: Is 2% Hydroxypropyhnethylcellulose a safe solution for intraoperative clinical applications? J. Cataract Refract. Surg. 12:679- 684:1986.
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[Figure - 1]
[Table - 1]