## 1 Introduction  
Nowadays, glaucoma represents the second leading cause of blindness worldwide Quigley and [PERSON] [1], caused by the progressive increase of the intraocular pressure (IOP) above 22 mmHg; a normal IOP range is within the 10 to 21 mmHg range. Ocular hypertension (OH) could be due to a physiologically increased production of aqueous humor or to an anatomical obstruction in drainage of the aqueous humor (AH) from the anterior chamber [2] (AC), towards the trabecular meshwork (Schlemm's canal), or in the uveoscleral pathway; the IOP then increases above normal, causing damage to the optic nerve [3, 4]. Various instruments, including corneal pachymeters [5], Humphrey visual field analyzers, gonioscopes [6], ophthalmoscopes [7], and tonometers [8], have been applied to diagnose glaucoma and the related damage.  
Different devices and methods for IOP measurement have been developed. Since its introduction, Goldmann explanation tonometry has been considered the gold standard for measuring IOP [8].  
However, accurate IOP measurements are highly dependent on patient cooperation and corneal characteristics, such as central corneal thickness (CCT), corneal curvature, hydration, elasticity, hysteresis, and rigidity [5; 9; 10; 11; 12], requiring real-time systems to know the biomechanical properties of the cornea to then compensate in the IOP measurement, such as with the ocular response analyzer (ORA; Reichert Ophthalmic Instruments, Depew).  
The use of lasers in biomedical applications has been growing steadily as the technology offers more stability, precision, and resolution in the measurements. For example, in ophthalmology, laser-induced breakdown (LIB) is used in procedures of intraocular microsurgery such as iridotomy, trabecipunction, intrastromal corneal ablation, posterior synechia, and posterior capsulotomy, among others [13; 14].  
The LIB phenomenon is the partial or complete ionization of a solid, liquid, or gas through thermal or electromagnetic excitation, producing a typical electron density (plasma) above \(10^{18}\)-\(10^{20}\) e/cm\({}^{3}\)[15]. While laser-induced thermal breakdown occurs for continuous-wave (CW) or repetitive-pulse lasers in [16; 17], optical breakdown occurs primarily for single short pulse exposures in the microsecond to femtosecond time regime [18; 19; 20]. In both cases, LIB in liquids generates cavitation bubbles, shock waves, and luminescence. The cavitation bubble grows to a maximum size, then collapses to generate a number of subsequent bubbles; this bouncing behavior generates shock waves on each bubble collapse.  
The focus of this work is about the implementation and validation of the spatial transmittance modulation (STM) technique [21; 22; 23] using a suitable IOP sensor applied to ex vivo pig eyes under normal and glaucoma conditions (IOP between 10 to 60 mmHg). The STM technique provides the bubble collapse time data accurately through optical intensity vs. time trace. In addition, the proposed technique was previously applied and validated using a pressure sensor in a cubic quartz chamber, and then in an artificial model of a human eye, with pressures from 0 to 300 mmHg above the atmospheric pressure [16; 23]. In this paper, we analyze and discuss the relationship between the induced IOP in ex vivo pig eyes and the cavitation bubble collapse time. We also study the cavitation bubble collapse time's dependence on the laser pulse energy. In addition, we performed an assessment of potential photo-damage caused on the cornea by the pump laser pulses.