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Published on: April 3, 2016
Effects of 7-methylxanthine on form-deprivation myopia in pigmented rabbits
Hao-Hui Nie1, Li-Jun Huo, Xiao Yang
1State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, SunYat-sen University, Guangzhou 510060, Guangdong Province, China.
Aim:
To determine the effect of 7-methylxanthine (7-MX) on the posterior sclera of form-deprivation myopia (FDM) in pigmented rabbits.
Methods:
Sixteen pigmented rabbits were monocularly deprived (MD) by suturing the right eyelids after natural eye opening (ten-day old) for a period of 30 days. Two groups of pigmented rabbits were fed either 7-MX (30 mg per kg body weight; n=8) or vehicle control (saline equal volume with 7-MX; n=8). Ocular refractions, axial lengths and body weights were measured at the start and the end of the experiment 30 days later. Electron microscopy was used to measure and determine the collagen fibril diameters in the posterior pole of sclera.
Results:
In vehicle control MD pigmented rabbits, 30 days of MD produced -1.10D±0.78D of myopia and the axial length increased 0.51mm±0.09mm. In MD pigmented rabbits fed with 7-MX, 30 days of MD induced only -0.21D±0.11D of myopia and the axial length increased 0.07mm±0.10mm. There was significant change in axial length of vehicle control MD pigmented rabbits (13.11mm±0.19mm versus 12.60mm±0.06mm; P=0.03). The changes in refraction and axial length of two MD groups' contralateral eyes during the 30 days were not significantly different (2.75D±0.27D versus 2.75D±0.35D, P>0.05; 12.60mm±0.06mm versus 12.45mm±0.14mm, P>0.05). The weights of the two groups pigmented rabbits had no significant changes (187g±22.1g versus 189g±19.3g, P>0.05). The diameter of scleral collagen fibers increased in both eyes of 7-MX treated pigmented rabbits. There was significant difference in collagen fibril diameters of inner layer (111.34nm±28.30nm versus 94.80nm±27.52nm, P=0.002) and outer layer (167.92nm±55.82 nm versus 144.04 nm±47.02nm, P=0.016) in the posterior sclera between the myopic eyes of vehicle control MD group and contralateral eyes of 7-MX treated MD group.
Conclusion:
7-MX appears to prevent FDM in pigmented rabbits by remodeling the posterior sclera.
Insights
7-methylxanthine (7-MX) significantly reduced form-deprivation myopia (FDM) in rabbits by altering posterior scleral collagen. This suggests 7-MX may prevent myopia progression through scleral remodeling.
Area of Science:
- Ophthalmology
- Pharmacology
- Biochemistry
Background:
- Myopia, a prevalent vision disorder, is often linked to axial elongation of the eye.
- Form-deprivation myopia (FDM) is a common experimental model used to study myopia development.
- The sclera plays a critical role in regulating eye growth and refractive development.
Purpose of the Study:
- To investigate the potential of 7-methylxanthine (7-MX) to prevent or mitigate form-deprivation myopia (FDM) in a rabbit model.
- To examine the effect of 7-MX on the structural properties of the posterior sclera in the context of FDM.
Main Methods:
- Form-deprivation myopia was induced in pigmented rabbits by monocular eyelid suture for 30 days.
- Rabbits were orally administered either 7-MX or a vehicle control.
- Ocular refraction, axial length, and posterior scleral collagen fibril diameters were measured.
Main Results:
- Vehicle control rabbits developed significant myopia (-1.10D) and axial elongation (0.51mm).
- 7-MX treated rabbits showed significantly reduced myopia (-0.21D) and axial elongation (0.07mm).
- 7-MX treatment led to increased collagen fibril diameters in the posterior sclera.
Conclusions:
- 7-methylxanthine (7-MX) demonstrates a protective effect against form-deprivation myopia in rabbits.
- The mechanism appears to involve the remodeling of posterior scleral collagen structure.
- 7-MX holds potential as a therapeutic agent for myopia prevention.
