Table 1. Pretreatment for ocular matrix.

Sample	Method	Pretreatment	Ref.
Tear	LC-MS	Vortex mixing Schirmer's strips in 9:1 MeOH/H2O; centrifuge and collect supernatant; dry; reconstitute	[30]
		Tear sample were centrifuged (14000 g, 10min, 4°C) in ice-cold 80% MeOH; supernatants were incubated on dry ice; evaporated; reconstitute	[38]
AH	LC-MS	Vortex-mixing for 1min equal volumes on the AH sample and freeze cold (-20°C) methanol/ethanol (1:1) mixture; stored on ice for 10min; centrifuge; collect supernatant and filter for analysis	[55]
		One volume AH mix with four volumes 100% ethanol; centrifuge; collect supernatant; lyophilization; reconstitute with aqueous solution	[23]
		One volume AH mix with five volumes ultrapure water; centrifuge; collect supernatant; analysis	[48]
	GC-MS	One volume AH mix with seven volumes 75% MeOH; vortex; centrifuge; collect supernatant and derivatize for analysis	[49]
	NMR	One volume AH mix with four volumes 100% ethanol; centrifuge; collect supernatant; lyophilization; reconstitute with DSS.	[23]
VH	LC-MS	One volume VH mix with four volumes acetone; store at -20°C overnight; centrifuge; collect supernatant; precipitation extract used 80% methanol and merge supernatant; freeze-drying; reconstitute with acetonitrile:methanol:isopropanol (4:4:1); sonic; centrifuge; collect supernatant and analysis	[92]
		One volume VH mix with four volumes 100% ethanol; centrifuge; collect supernatant; add 1/2 chloroform and same volume water; centrifuge; lyophilization; reconstitute with water	[23]
	NMR	One volume VH mix with four volumes 100% ethanol; centrifuge; collect supernatant; add 1/2 chloroform and same volume water; centrifuge; lyophilization; reconstitute with D2O containing DSS and phosphate buffer	[23]
Cornea	LC-MS	Samples were rinsed in 1×PBS and lysed with ice-cold 80% methanol; incubated on dry ice for 15min and homogenized; centrifuged; collect supernatant; analysis	[80]
	NMR	The proteins in cornea samples were precipitated by EtOH; the lipids were removed from the protein-free cornea extracts using the chloroform/EtOH/water mixture; centrifuged; lyophilization; reconstitute with D2O containing DSS and phosphate buffer	[67]
Lens	LC-MS	Lens homogenate with pre-cooled EtOH; centrifuged; collect supernatant; pellet extracted again; merge supernatant; dry; reconstitute with water	[72]
		Lens homogenate with pre-cooled EtOH; centrifuged; collect supernatant; pellet extracted again; merge supernatant; to remove lipids from the extract, H2O and CHCl3 was added to the combined supernatant, shaken, then H2O was added; centrifuged; collect supernatant; lyophilized; re-dissolved in aqueous solution	[71]–[72]
	NMR	Lens homogenate with pre-cooled EtOH; centrifuged; collect supernatant; pellet extracted again; merge supernatant; dry; reconstitute	[72]
		Lens homogenate with pre-cooled EtOH; centrifuged; collect supernatant; pellet extracted again; merge supernatant; to remove lipids from the extract; H2O and CHCl3 was added to the combined supernatant, shaken, then H2O was added; centrifuged; collect supernatant; lyophilized; re-dissolved in D2O containing DSS and phosphate buffer	[71]–[72]
Retina	LC-MS	Retina homogenate with 80% MeOH; incubate on ice; centrifuge; collect supernatant; lyophilized; reconstitute with mobile phase (A:B=4:6)	[26]
		Add 800 µL of chloroform:methanol (50:50, pre-cooled to -20°C) to retina samples; homogenate; 400 µL of water was added to the mixture; centrifuge; collect bottom lipophilic layer; lyophilized; reconstituted in 200 µL 50:50	[27]
		Retina homogenization with 40 µL water; centrifuged; 5 µL of the supernatant were transferred for protein quantitation and 140 µL of methanol were added; homogenize; centrifugate; collect supernatant and spin-dried for 24h; reconstitute with water	[17]
		Add 140 µL extraction buffer [methanol:chloroform:H2O (700:200:50)] to the retina sample; homogenize; centrifuge; collect supernatant; spin-dry; suspended in 100 µL of mobile phase (40% of A and 60% of B) with vortex for 10s	[16]
	GC-MS	Retina homogenate with 80% MeOH; incubate on ice; centrifuge; collect supernatant; lyophilized; derivatize	[26]
		Add 800 µL of chloroform:methanol (50:50, pre-cooled to -20°C) to retina samples; homogenate; 400 µL of water was added to the mixture; centrifuge; collect top hydrophilic layer; lyophilized; derivatize	[27]

LC-MS: Liquid chromatograph-mass spectrometer; GC-MS: Gas chromatograph-mass spectrometer; NMR: Nuclear magnetic resonance; AH: Aqueous humor; VH: Vitreous humor.