WO2001005327A2

WO2001005327A2 - New intraocular lens

Info

Publication number: WO2001005327A2
Application number: PCT/EP2000/006486
Authority: WO
Inventors: Marrie Van Der Mooren; Charlotta ZETTERSTRÖM; Sverker Norrby
Original assignee: Pharmacia Groningen Bv
Priority date: 1999-07-20
Filing date: 2000-07-19
Publication date: 2001-01-25
Also published as: AU6562400A; WO2001005327A3

Abstract

The present invention is directed to an intraocular lens for pediatric use adapted for implantation in the capsular bag of eye of an infant, preferably of about up to the age of two months. After implantation in the eye, the lens will effectively obstruct the formation of secondary cataract and minimize any interference with the ocular growth of the infant or neonate eye.

Description

New Intraocular Lens

Field of invention

The present invention relates to an intraocular lens (IOL) that is specifically designed to be implanted in the capsular bag of an infant of about 0 to 2 months age.

Background of the invention

In cases with severe developmental and traumatic cataracts (impairments of the natural crystalline lens of the human eye), refined surgical techniques and materials have been developed for removing the defective lens and implanting a synthetic intraocular lens (IOL) of a predetermined, suitable refractive power in the capsular bag of the eye. A number of different lens implants which are made of biocompatible materials, such as polymethylmethacrylate (PMMA) or silicones are commercially available. Generally, these IOLs comprise an optical body having an optical part with a predetermined refractive power and haptic means for securing the implant in the capsular bag. Many types of such IOLs have been suggested with different designs, flexibility and characteristics that facilitate their insertion through a surgical incision in the eye. Most frequently, the development of a cataract is a degenerative disorder from which elderly persons suffer, but in certain cases also newborns or infants are subjected from an impaired lens complication named unilateral congenital cataract. An impaired vision during the formative period of human senses may affect the normal development of the eye and result in deep amblyopia (lazy eye). The presently accepted treatment of congenital cataract is prompt optical correction and an aggressive occlusion therapy with regular follow-up. This is a quite complex and demanding therapy which at worst may cause complications such as the development of secondary glaucoma in the eye(s) having the defect lens removed, but not replaced with an implant lens until the eye has grown sufficiently. It is therefore a demand for alternative therapies in particular for infants of 0 to 2 months age. A feasible therapy for infants older than one year is surgically removing the defect lens from the capsular bag and immediately implanting an IOL through an incision into the capsular bag and positioning it with its haptic means. In Journal of Cataract Refractive Surgery, 1997, Vol. 23 (1), pp. 618-622 (E Dahan et al.) it is reported a refractive study of children having undergone implantation of intraocular lenses in the posterior chamber of the eye. The children had received lenses of sizes between 10.5 and 12.0 mm having optical plates between 5.5 and 6.5 mm dependent on their age. The lenses of the study were of the same overall design as adult lenses. In the discussion of the article it is acknowledged that there is a need for smaller, especially designed pediatric IOLs and that normal adult IOLs can cause excessive pressure on uveal structures when they are placed in the sulcus. Furthermore adult IOLs can decenter because their haptics are often compressed unevenly in the small eye of the child. It has also been reported that regular sized IOLs retard the natural axial growth of the eye in rabbits (J Cataract Refract Surg 1997, Vol.23 (Suppl. 1, pp. 635-640 (U Kugelberg et al.)). There is also risk that the uneven pressure exerted from the haptics of large adult size IOL can inflict damages on the fragile tissues of the growing eye of infants. It is therefore a need for an IOL adapted to for the implantation in the capsular bag of infants having an age of about 0 to 2 months which is capable of minimizing secondary cataract triggered by the proliferation of epithelial and of minimizing the influence on the ocular growth.

Description of the invention

The present invention is directed to an intraocular lens for pediatric use comprising an optical part and two arcuate haptic means adapted for implantation in the capsular bag of the infant eye, in which the haptic means, when compressed by the eye, after its implantation, together form a substantially full circle in crossection. It is to be understood that the shape of the eye and its compressive forces can vary among different individuals. For this reason, it is obvious to the skilled person that an exactly full circle will not always be obtained. In some individuals the haptic means will be somewhat more compressed than intended and the two arcuate haptic means will make a small overlap or come in contact, resulting in that their combined shape will deviate from a perfect circle, but remains substantially circular. In a similar manner a lower compression or small eye leads to that circle remains unclosed. The mentioned small deviations from a perfect circle are to be regarded as substantially full circles within the context of the present invention, and they have no, or very limited, functional consequences for the performance of the lens which will be explained below in greater detail.

It is an important aspect of the present invention that the intraocular lens has a haptic angle of at least 10°, or preferably at least 15° and most preferably about 20°. The haptic angle is defined herein as the angle between the haptic means and plane perpendicular to the optical axis of the lens.

It is a characteristic feature of the presently invented intraocular lens that it comprises two identical arcuate flexible haptic means connected to its optical part through two diametrically opposite haptic junctions such that lens is completely enclosed within a circle in its non-compressed state. The haptic means thereby preferably extend until they reach an equator plane of the lens in its non-compressed state. The angle between a haptic means and the equator plane preferably is about 180°.

It is a further characteristic feature of the presently invented intraocular lens that it size is reduced in comparison to adult lens in order comply with the dimensions of the infant eye, in particular the eyes of neonates of the age of between 0 to 2 months. Preferably, the diameter of the mentioned enclosing circle is less than about 8 mm and more preferably between about 7 and 8 mm. The diameter of the optical part of lens is suitably less than about 5 mm and preferably between about 4 and 5 mm.

It is another aspect of the present invention that the haptic means have a part with reduced width compared to the part extending from the haptic junctions and that the haptic means have end points with increased width. Preferably, the haptic means have a first part extending from the haptic junctions to about half of their total length and a second part with reduced width compared to said first part. A preferred reduction in width of the second part of the haptics is from about 15 to 25% compared to the first part extending from the haptic junctions. The haptic means can further comprise a third part having a larger width than any of their first and second parts. The third part normally constitutes the end part of haptic means and is designed to make the handling of the lens with a forceps easier for the surgeon during its insertion.

Detailed description of the invention

Fig. 1 is a side view of a pediatric IOL according the present invention. Fig. 2 is an IOL according to the present invention seen from above.

As best seen in Fig. 2, a preferred embodiment of an IOL according to the present invention has a central circular lens body ( 1 ) with an optical part of a predetermined refractive power and two identical flexible haptic means (2) and (3). The haptic means are connected to the lens body by two diametrically opposite haptic junctions (4) and (5). In this embodiment the lens body and the haptic means is made in one piece of PMMA- HSM (polymethylmethacrylate lens treated with a heparin coating process) according to a compression molding technology.

With reference to the preferred embodiment of the present invention of Fig. 1, the haptic means are extended forwards of the lens body (to the front of the eye) and they have both an haptic angle of 20° which is defined as the angle between the haptic means and plane perpendicular to the optical axis of the lens. The haptic angle is considerably larger than in adult lenses selected to obtain the optimal anatomic fit in infants of the age of about 0 to 2 months, while at the same time providing for the possibility to design lenses with different optical powers and thicknesses with a sufficient distance to the iris. It is also important to select a haptic angle that enables an easy surgical insertion of the lens. The length and the shape of haptics are characteristic parts of the present invention and their specific design contribute to prevent secondary cataract caused by growth of epithelial cells and their specific compressibility to a circle or a substantially circular shape serve to minimize the obstruction of the ocular growth of the infant eye. In its non-compressed state before implantation, each of the two haptic means of the lens has an identical arcuate shape which is close semi-circular given that they extend until they reach the equator plane (6) and thereby substantially have an angle of 180° to such a plane. In the non-compressed state of Fig. 2, the lens is entirely enclosed within a circle having a diameter of 7.8 mm. This lens is designed so it can be compressed to a circle of 7.0 mm after being implanted in the capsular bag of an infant eye. The haptic means have been designed with varying width from the haptic junction to their end. In the lens embodiment of Fig. 2, the haptic means has a first part with an initial width of 0.15 mm from the haptic junction to half of the total length of the haptic means and a second part with a reduced width of 0.12 mm extending until a position close to the end of haptic means diametrically opposite from the haptic junctions at which the width again increase from 0.12 mm to 0.16 mm in a third part of the haptic means. In this embodiment the length of the third part is about 2 mm. The second part with reduced width imparts an improved flexibility of the haptic means, which will ease the insertion of lens in the capsular bag. The differences in width along the haptic leads to that the reaction forces of the haptic means against the capsular bag will not be perfectly identical at all positions. However, this has not practical consequences for the performance of the lens and its mentioned characteristics.

Intraocular lenses having the above disclosed features will, after surgical insertion in the eye, effectively obstruct the formation of secondary cataract and minimize any interference with the ocular growth of the infant or neonate eye.

Claims

1. An intraocular lens for pediatric use comprising an optical part and two arcuate haptic means adapted for implantation in the capsular bag of the infant eye characterized in that the haptic means when compressed by the eye forms a substantially full circle in crossection.

2. An intraocular lens according to claim 1 characterized in that its haptic angle is at least 10°.

3. An intraocular lens according to claim 2 characterized in that its haptic angle is at least 15°, preferably about 20°.

4. An intraocular lens according to claim 1 characterized in that it comprises two identical arcuate flexible haptic means (2), (3) connected to its optical part (1) through two diametrically opposite haptic junctions (4), (5) such that lens is completely enclosed within a circle in its non-compressed state.

5. An intraocular lens according to claim 4 characterized in that the haptic means (4), (5) extend until they reach an equator plane (6) in its non-compressed state.

6. An intraocular lens according to claim 5 characterized in that the angle between the haptic means and the equator plane substantially is 180°.

7. An intraocular lens according to claim 4 characterized in that diameter of the circle is less than about 8 mm.

8. An intraocular lens according to claim 1 characterized in that the haptics means have a part with reduced width compared to the part extending from the haptic junctions.

9. An intraocular lens according to claim 8 characterized in that the haptic means have a first part extending from the haptic junctions to about half of their total length and a second part with reduced width.

10. An intraocular lens according to claim 8 characterized in that the haptic means having a reduction in width of about 15 to 25% compared to the part extending from the haptic junctions.

11. An intraocular lens according to claim 10 characterized in that the haptic means further comprise a third part having a larger width than any of their first and second parts.

12. An intraocular lens according to claim 12 characterized in that the third part of the haptic means constitutes their end parts.

13. An intraocular lens according to claim 1 characterized in that the diameter of the optical part is less than 5 mm.