Mr. D. Griffin on an unusual Affection of the Eye. 283 



The effect, however, produced was such as would result 

 from a distortion or bending back of the upper part of the 

 crystalline lens, producint^ an effect not exactly like spherical 

 aberration, but like what would arise from the axis of that 

 part of the lens losing its parallelism to the axis of the centre 

 and other parts, which would tend to throw the image pro- 

 duced by that part in the direction in which the distortion of 

 the axis lay. 



In order that a correct idea may be formed of the degree 

 of the displacement, it is necessary to mention that the letters 

 which I looked at, at the distance of three yards, and of which 

 the different images were separated to the degree mentioned 

 above, were about |ths of an inch in height and about the same 

 in breadth. 



The only thing that occurred to me that could produce 

 such a distortion was the pressure of the upper eyelid on the 

 eyeball, which was very considerable and long continued. 

 That the distoj'tion was in the lens alone seems probable, be- 

 cause, from its half-solid state, it is almost the only part of 

 the eye that would retain the effect of pressure for any time ; 

 but if the altered shape of the lens was the cause, the altera- 

 tion must have been an exceedingly peculiar one. To pro- 

 duce the three images above mentioned it must have had two 

 sudden bendings backwards; one somewhere near the middle, 

 and the other near the upper edge. The lower half, which 

 1 suppose to have been undisturbed, would in that case have 

 given the true image ; the part immediately above, which was 

 bent backwards in some degree, would have formed an image 

 lower on the retina, and therefore higher to the perception 

 than the true one; and the highest part, or upper edge, of the 

 lens, which was most distorted, would have given the lowest 

 image on the retina, and therefore the highest to the perception. 

 But here came the difficulty : on considering the structure of 

 the lens as far as that is at present known, and how its density 

 lessens gradually from the centre to the circumference, it 

 seemed extremely hard to suppose that any bending could 

 take place in it otherwise than very gradually, and in a re- 

 gular curve. This gradual bending, it is evident, would not 

 be indicated by the perception of multiplied images, but by 

 great indistinctness and haziness in the upper part of the ob- 

 ject; yet of either haziness or deficiency of outline in the images 

 there was not the least appearance. 



I have tried repeatedly since to produce the same appear- 

 ance by simply covering the left eye while using the right, and 

 otherwise observinjx the same circumstances, but 1 found that 



2 02 



