"most striking alteration" is correct and usable in written English.
You can use it to describe something that has changed significantly from its former state. For example, "The most striking alteration in the new product design was the addition of a touchscreen interface."
The most striking alteration besides the retinal degeneration was hypotrophy of the fat body in old TTR-A/TTR-A flies (compare Fig. 2A with B and Fig. 4A with B), reflected by decreased size, fewer lipid droplets and empty spaces which by shape and size suggested missing fat body cells (Fig. 4B, asterisks).
The most striking alteration was a 74-fold induction of the amphiregulin gene which was accompanied by lower low levels of induction were observed for HSP70, P21CIP1 and the gene for acidic fibroblast growth factor.
The most striking alterations in the versions of the film are the addition of more folk music, and the change (suggested by Zanuck) that Earp and Clementine part at the end with a chaste kiss rather than the friendly handshake that had drawn laughter at the first screening.
In contrast, acute HS without volume resuscitation resulted in the most striking alterations in lung mechanics, haemodynamics, as well as weight changes.
The most striking change had been made earlier, however.
The excretion pathway is the most significant differentially expressed pathway in ccRCC in terms of overall rank, indicating that loss of normal renal function is the most striking biologic alteration.
The most striking genetic alterations identified were the presence of both GNAS and KRAS mutations in every low-grade MCP.
One of the most striking functional alterations observed in T cells is the decrease of the production of IL-2.
Most striking were alterations within the uncinate fasciculus in those with MAPT mutations, which persisted when compared with AD and C9ORF72 groups.
Although the two RPI1 alleles differ by several nucleotide changes, the most striking difference is the alteration in the size of a repeat region present in the coding sequence of the gene.
Our most striking observation, however, was the alteration in PDGF/Abl signaling.
