OPTHALMIC COMPOSITION

Abstract: Ophthalmic composition for use in ocular surgery. The composition comprises an aqueous solution of sodium hyaluronate with a concentration within the range of 18 - 40 mg sodium hyaluronate/ml solution and the molecular mass of sodium hyaluronate being in the range of 1x10<6> - 10x10<6> <M>r,M. The invention also relates to a method for conducting ocular surgery characterized in that the composition is introduced into the eye as a surgical aid. The invention further relates to a method for conducting cataract surgery.

Description: Ophthalmic composition The present invention relates to an ophthalmic composition for use in ocular surgery and a method for conducting ocular surgery. In particular the invention relates to a composition of sodium hyaluronate with a specifically defined molecular mass and concentration, for use in ocular surgery . Intraocular lens implantation has today become routine surgery. A major tool to accomplish this was the introduc- tion of Healon® (1980) , the high molecular mass, viscoelas- tic, noninflammatory preparation of sodium hyaluronate. Since then the cataract surgery has undergone a tremendous progress and many viscoelastic products have been developed. Typically these products are aqueous solutions con- taining a polysaccharide such as sodium hyaluronate, sodium chondroitin sulfate and hydroxypropylmethylcellulose, at concentrations varying from 10-70 mg/ml . The molecular mass (expressed as mass average relative molecular mass, <M> r t ι_) varies from about 20.000 (chondroitin sulfate) to about 5.000.000 (sodium hyaluronate). A cataract surgery of today can be divided into several steps. The first step is pupil dilatation and local anaesthesia. The operation starts by making an incision into the anterior chamber of the eye. When the eye is punctured, the aqueous humour leaks out and the anterior chamber becomes shallow. A viscoelastic product is injected into the anterior chamber, which then regains its former shape and depth. The viscoelastic product maintains the anterior chamber and protects the vulnerable tissues especially the endothelial cells on the cornea. The next step is to make a hole in the anterior lens capsule, a capsulotomy, which can be done in several ways. The viscoelastic helps the surgeon by creating enough space by maintaining the anterior chamber depth and to stabilize the lens . Extraction of the lens nucleus can be done in different ways, e.g. planned ECCE (extracapsular cataract extrac- tion) or phacoemulsification (phaco) using ultrasound. The remaining lens cortex is removed by irrigation/aspiration. - After removal of the lens, viscoelastic product is again injected to inflate the capsular bag and to deepen the anterior chamber to make space for the intraocular lens implantation. The viscoelastic product maintains the space in the anterior chamber and is a very important protector of the endothelial cells and of other intraocular tissues from direct contact with the lens . Upon completion of surgery the viscoelastic product is removed from the eye by irrigation/aspiration and substituted by physiological salt solution. If needed the wound is ' sutured. Planned ECCE is the term normally used when the lens 'nucleus is removed in one piece. Planned ECCE requires an incision size of 9 -12 mm. In the method by phaco the lens nucleus is disintegrated with the help of ultrasound and is aspirated through a small incision, usually approximately 3 mm. An intraocu- lar lens, foldable or not foldable, is then implanted through the incision. Phaco is the most modern method, which has increased rapidly in popularity due to the improved patient outcome. The small incision needed, reduces the amount of astigmatism induced by the surgery. Phaco is the most commonly employed technique in most countries and it will be the dominating technique for the foreseeable future. The demands on the viscoelastic products used in the surgical steps mentioned above are different. Current vis- coelastic products can be divided into two broad groups . The first is a group of highly viscous cohesive products containing high molecular mass polysaccharides that already at moderate concentrations (about 1 mg/ml) form flexible entangled molecular network and which have a high zero- shear viscosity. The second group consists of lower zero- shear viscosity dispersive products containing low molecular mass polysaccharides in high (about 70 mg/ml) concentrations, which tend to disperse in the eye and which do not exhibit cohesive properties even at high concentrations . The dispersive products typically contain high concentration (approximately. 70 mg/ml) of low molecular mass poly- saccharides (average mass average relative molecular mass about 200 000) . These products fracture easily and stay in the anterior chamber during the turbulent phacoemulsifica- tion procedure. However, these products have poor space maintaining properties. Furthermore, these products can not easily be removed from the anterior chamber at close of surgery, and frequently require high pressure to expel from the syringe through an ophthalmic cannula into the anterior chamber . The cohesive products contain high molecular mass poly- ' saccharide (mass average relative molecular mass: 1 to 5 million) at low concentration (10-15 mg/ml) . The latter products can easily be injected through thin cannulas, and exhibit good space-maintaining properties. They can also easily be extracted from the anterior chamber due to the cohesive properties. However, as a consequence of the cohesive properties these products frequently leaves the chamber as a chunk during the turbulent phacoemulsification procedure . The cohesive viscoelastic products are used to displace and stabilize tissues and to pressurize the anterior chamber. However, there is a risk that they leave the eye too quickly during phaco and leave the endothelium not well protected. On the contrary, the dispersive viscoelastic products stay in the anterior chamber during phaco but do not stabilize tissues very well. So far none of the viscoelastic products available have been able to match all viscoelastic needs during cataract surgery with phacoemulsifi- cation and it has been assumed impossible to make such a product . To achieve the optimal viscoelastic effect in all the surgical steps US 5,273,056 suggests to use different viscoelastic products in the various steps. US 5,273,056 uses a combination of both cohesive and dispersive viscoelastic products. A similar solution has been suggested by Dr. Steve A. Arshinoff in the description of the M soft-shell ' ' - technique (Ocular Surgery News, International edition, vol. 14 no. 18 1996, p. 17, "Soft-shell" technique uses two types of viscoelastic products" reported by Harvey Black) The object of the present invention is to obtain an improved ophthalmic composition for use in ocular surgery. Further, the object with the present invention is to present a viscoelastic product that could be used in all steps of cataract surgery, especially cataract surgery with phacoemulsification. The object of the present invention is to obtain a viscoelastic product which combines dispersive and cohesive qualities. Yet a further object of the invention is an improved 'method of ocular surgery. The objects of the invention are achieved by the composition and the method as claimed in the claims. According to the present invention an ophthalmic composition for use in ocular surgery is obtained. The composi- tion comprises an aqueous solution of sodium hyaluronate with a concentration within the range of 18-40 mg sodium hyaluronate/ml solution and the molecular mass of sodium hyaluronate being in the range of 1x10 - 10x10 M> r M- According to a further aspect of the invention use of an aqueous solution of sodium hyaluronate with a concentration within the range of 18 - 40 mg sodium hyaluronate/ml solution and the molecular mass of sodium hyaluronate being in the range of 1x10 6 - 10x106 <M> r f jyj, for the manufacture of a composition for ocular surgery is obtained. According to yet a further aspect of the invention a method for conducting ocular surgery is obtained. According to the method a composition comprising an aqueous solution of sodium hyaluronate with a concentration within the range of 18 - 40 mg sodium hyaluronate/ml solution and the mo- lecular mass of sodium hyaluronate being in the range of 1x10 6 - 10x106 <M> r M is introduced into the eye as a surgical aid. to t o n o o tr tn TJ rt Hi tr ? tr tn rt in Ω Hj PJ & CL tr 0 tr μ- rt in μ- rt Hi 0 PJ 0 PJ 3 J 0 tr d φ ^ Φ Φ rt tr μ- o J IQ d d Φ Ω ^ P tr rt P tr PJ hh P tr P φ tn PJ Hi PJ rt tn Φ φ < φ CL PJ PJ Hi in d PJ Ω J Φ φ P PL rt rt rt d Ω tr Ω 3 • μ- TJ φ 3 μ- μ- r- μ- μ- Hi rt TJ in LQ tn PJ Φ tr TJ H rt 0 d tr PJ <! 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TJ 3 rt rt 0 rt P ^ P 0 Ω • *< d P tn PJ μ- rt Ω TJ H- 1 PJ » iQ Φ 0 tr μ- tr d PJ Φ tn φ < 0 μ- h PJ μ- μ- hh - 1 P tr rt φ Ω μ- en Ω tn Φ 0 μ- 01 P TJ φ hti P rt 3 0 μ . J rt rt in hh PJ tn LQ φ μ- Ω tr tn m in ≤ ; rt μ- Hi P P 01 Ω tr P 0 in P tr μ- Ω O P μ- PJ rt μ- Φ rt tn μ- PJ PJ rt H φ tn d Φ in μ- Φ 3 Ω rt rt hh iQ hh 3 tr Φ in rt hh PL μ- £ rt 0 P TJ <; μ- 03 P tr P tr rt tn 0 PJ Ω tr Hi μ- σ 0 T 0 tr 0 0 μ- tr h-' Ω 01 μ- rt 0 Φ rt rt μ- PJ 3 Hi rt rt 0 φ Φ Φ Ω Φ rt ω PL d μ- P rt φ μ- d μ- d p P 0 rt rt J φ μ- tr tr φ hh Hi tr μ- rt P P tr rt 01 in 0 -> 0 tr Φ tr Hi 0 PJ φ TJ hh 0 d tr CL d μ- μ- μ- φ PJ lυ P hh rt PJ Ω P rt 1 tr Φ Ω hh 3 Φ tn P 0 0 PJ LΠ tr ^ μ- rt 0 J Ω 0 φ P P μ- P φ tn rt CL tn mg/ml, most preferably within 20 - 28 mg/ml and the molecular mass of the sodium hyaluronate is preferably within the 6 6 F, range 1x10 - 6x10 <M> r/M , most preferably within 2.5x10 g - 5x10 <M> r> M, • The ophthalmic composition according to the invention can be used in all types of ocular surgery, such as cataract surgery, glaucoma surgery, vitreous surgery and posterior segment surgery. The cohesive qualities of the present composition are very suitable in glaucoma, vitreous and posterior segment surgery both as a protector of eye tissue and to move and hold tissue away from the operation area and as an antiadherence product. However, the composition is ' especially suitable for cataract surgery with phacoemulsification. Thus, in a preferred embodiment of the present ' invention step c) in the above mentioned method is made by phacoemulsification. At the end of the surgery the composition according to the invention is preferably removed from the eye, but can be left in special cases. The composition according to the invention is prepared in a conventional manner by dissolving the sodium hyaluronate in an aqueous solvent containing physiological amounts of sodium chloride to the required concentration of sodium hyaluronate. Sodium hyaluronate of suitable molecular mass is today a commercially available product. The solvent may also contain other inorganic salts such as calcium-, magnesium- and potassium chloride in physiological concentrations. Suitably the solvent may also contain buffering agents such as phosphate, acetate, carbonate or citrate in physiological concentrations. The solvent may also contain other physiological compounds. As mentioned above the composition has a good protecting effect against the free radicals produced during phaco. In order to increase this protective effect a compound acting as a scavenger can be added to the composition. As suitable scavengers can be mentioned superoxidedismutase (SOD), mannitol, glutathione or other known scavanger compounds acceptable to the eye . The invention will now be illustrated with the following examples which however, are not intended to restrict the invention. Example 1 : Two sodium hyaluronate solutions A and B were prepared accordingly: Solution A g Sodium hyaluronate <M> r ,__ = 3x10 20 mg Sodium chloride 8,5 mg Disodium phosphatedihydrate 0,28 mg Monosodium phosphatemonohydrate 40 μg Water suitable for injection solutions to obtain 1 ml pH = 7.0-7.5 Solution B 6 Sodium hyaluronate <M> r M = 3x10 25 mg Sodium chloride 8 , 5 mg Disodium phosphatedihydrate 0,28 mg Monosodium phosphatemonohydrate 40 μg Water suitable for injection solutions to obtain 1 ml pH = 7.0-7.5 These compositions were compared with the following commercially available products: Viscoat® (Alcon Surgical Inc.): Composition according to the manufacturer: Sodium chondroitin sulfate 40 mg/ml <M> r,M = 25000 Sodium hyaluronate 30 mg/ml <_. r,M = 500.000 pH = 6.2-7.8 Amvisc Plus® (Chiron Vision) : Composition according to the manufacturer: Sodium hyaluronate 16 mg/ml <M r,M = 1.5x10 pH = 6.4 (non-buffered) HealonGV® (Pharmacia & Upjohn) : Composition according to the manufacturer: Sodium hyaluronate 14 mg/ml < M > r,M = 5xl0 pH = 7.0-7.5 Ocucoat® (Storz Ophthalmics, Ine . ) : Composition according to the manufacturer: Hydroxypropylmethylcellulose 20 mg/ml <M> r ,M = 80.000 pH = 6.8-7.5 The solutions were tinted by fluorescein and filled in syringes . The materials were tested by an in-house excellent lab. technician and seven skilled ophthalmic surgeons, in masked trials, on pig and human cadaver eyes. The performance of all products in the different surgical steps and the overall assessment were established on a scale 0 - 100 where 0 = worthless, 100 = excellent: Step Viscoat Amvisc HealonGV Solution Solution Ocucoat Plus B A Injecti 16 93 93 74 85 80 on Capsulo 70 56 79 93 83 33 rhexis Phaco 66 47 21 82 66 17 IOL* 66 73 96 91 98 25 Removal 21 51 93 65 86 20 Overall 42 45 59 86 88 30 . *In ra ocular lens implantation The result can also be visualized in the following way, where + denotes better than average and - worse than average : Injecti Capsulo Phaco IOL Removal Overall on rhexis Viscoat - + + Ocucoat Amvisc plus Healon GV Solutio n A Solutio n B From the result it is evident that both solution A and B according to the invention exhibit a very satisfactory performance in all steps of surgery. Example 2 : Further sodium hyaluronate solutions according to the invention were prepared in the same manner as in example 1 with different molecular mass and concentrations. The solutions were tested by the skilled lab. technician or a skilled ophthalmic surgeon. The following overall assessment was obtained: Solution Concentration <M> r ,M Overall 6 (mg/ml) (10 ) assessment Solution C 18 3.5 85 Solution D 19 1 100 Solution E 19 2 100 Solution F 35 1 100 From these result it is evident that other sodium hyaluronate solutions within the claimed range work equally well .

Claims: Claims 1. Ophthalmic composition for use in ocular surgery characterized in that it comprises an aqueous solution of sodium hyaluronate with a concentration within the range of 18 - 40 mg sodium hyaluronate/ml solution and the molecular mass of sodium hyaluronate being in the range of 1x10 10x10 <M> r/ M- 2. Ophthalmic composition according to claim 1, characterized in that the molecular mass of the sodium hyaluro- 6 6 nate is 1x10 - 6x10 <M>χ ι _ _ and the concentration of the aqueous solution 18 - 35 mg/ml. 3. . Ophthalmic composition according to claim 1, characterized in that the molecular mass of the sodium "hyaluro- 6 6 nate is 2.5x10 - 5x10 < > r jv] and the concentration of the 'aqueous solution 20 - 28 mg/ml. 4. Ophthalmic composition according to any of claims 1 - 3, characterized in that it further comprises a compound acting as a scavenger. 5. Ophthalmic composition according to claims 1 - 4 for use in cataract surgery. 6. Ophthalmic composition according to claims 1 - 5, for use in cataract surgery with phacoemulsification. 7. Ophthalmic composition according to claims 1 - 4, for use in glaucoma surgery, vitreous surgery or posterior segment surgery. 8. Use of an aqueous solution of sodium hyaluronate with a concentration within the range of 18 - 40 mg sodium hyaluronate/ml solution and the molecular mass of sodium hyaluronate being in the range of 1x10 6 - 10x106 <M> r/ ^,for the manufacture of a composition for ocular surgery. 9 A method for conducting ocular surgery characterized in that a composition comprising an aqueous solution of sodium hyaluronate with a concentration within the range of 18 - 40 mg sodium hyaluronate/ml solution and the molecular g mass of sodium hyaluronate being in the range of 1x10 c 10x10 <M> r M is introduced into the eye as a surgical aid. 10. A method for conducting cataract surgery in an eye having an anterior chamber, a posterior chamber and a lens capsule, the method comprising the following steps: a) entering the anterior chamber by making an incision and injecting a composition comprising an aqueous solution of sodium hyaluronate with a concentration within the range of 18 - 40 mg sodium hyaluronate/ml solution and the molecular mass of sodium hyaluronate being in the range of 1x10 6 - 10x106 <M> r/ M into the anterior chamber; b) performing a capsulotomy; c) removing of lens and lens cortex; d) injecting into the lens capsule the composition used in" step a) and implanting an intraocular lens; e) optionally, removing the composition injected in ' steps a) and d) . 11. A method of claim 10, characterized in that step c) is made by phacoemulsification. 12. A method according to claims 9-11, characterized in that the molecular mass of the sodium hyaluronate is 1x10 c - 6x10 < > r/ ji and the concentration of the aqueous solution 18 - 35 mg/ml. 13. A method according to claim 9-11, characterized in that the molecular mass of the sodium hyaluronate is 2.5x10 6 - 5x106 <M> r M and the concentration of the aqueous solution 20 - 28 mg/ml. 14. A method according to any of claims 9 - 11, characterized in that the composition further comprises a compound acting as a scavenger. 15. A method according to any of claims 9, 12-14, char- acterized in that the ocular surgery is glaucoma surgery, vitreous surgery or posterior segment surgery.

Inventors: FERGEUS SUSANNA, LUNDBERG KERSTIN, WIK OVE, FERGEUS, SUSANNA, LUNDBERG, KERSTIN, WIK, OVE
Applicants: PHARMACIA & UPJOHN AB
Application year: 1998
Main classification: A61K31
IPC codes: A61F2, A61F9, A61K9, A61K31, A61K47, A61P27, C08B37