( Light ( ( ( ( ( ( enters ( through ( ( the ( clear ( front surface ) ) ) ( of ( ( the eye ) ( -LRB- ( ( the cornea ) -RRB- ) ) ) ) ) ) ) , ) ( passes ( ( ( through ( ( the opening ) ( of ( the pupil ) ) ) ) , ) ( through ( the lens ) ) ) ) ) and ) ( finally ( is ( perceived ( by ( ( the retina ) ( in ( ( the back ) ( of ( the eye ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Light)) (VP (VP (VBZ enters) (PP (IN through) (NP (NP (DT the) (JJ clear) (NN front) (NN surface)) (PP (IN of) (NP (NP (DT the) (NN eye)) (PRN (-LRB- -LRB-) (NP (DT the) (NN cornea)) (-RRB- -RRB-))))))) (, ,) (VP (VBZ passes) (PP (IN through) (NP (NP (DT the) (NN opening)) (PP (IN of) (NP (DT the) (NN pupil)))) (, ,) (PP (IN through) (NP (DT the) (NN lens))))) (CC and) (VP (ADVP (RB finally)) (VBZ is) (VP (VBN perceived) (PP (IN by) (NP (NP (DT the) (NN retina)) (PP (IN in) (NP (NP (DT the) (NN back)) (PP (IN of) (NP (DT the) (NN eye)))))))))) (. .)))
Light enters through the clear front surface of the eye (the cornea), passes through the opening of the pupil, through the lens and finally is perceived by the retina in the back of the eye.
(ROOT (S (NP (DT The) (NN pupil)) (VP (VBZ is) (NP (NP (DT the) (NN name)) (PP (IN of) (NP (NP (DT the) (JJ black) (NN opening)) (PP (IN in) (NP (NP (DT the) (NN eye)) (SBAR (WHNP (WDT that)) (S (VP (VBZ lets) (SBAR (S (NP (NN light)) (VP (VBP enter))))))))))))) (. .)))